Hey guys, new here.
So what's the consensus on the best EV spread for AV Slowbro? I'm thinking 252 in both HP and Atk, since he already has good Def, and his SDef will be bolstered by AV.
By Atk I hope you mean Sp Atk o.o
Nope, the actual stats are all that matter. Think of Assault Vest as an artificial modifier, rather than a true +1 Sp DefenseHow do Download and Assault Vest interact with each other? If a target Pokemon, say Conkeldurr, does the Download user, like Genesect, still get a Special Attack boost even though Conkeldurr's Special Defense would be higher than its uninvested Defense?
So when an AV Pokemon is out on the field, if its final SpDef is higher, then Download should give me an Attack boost?
Conkeldurr is, by far, the best user of this thing. Nothing likes to switch into Knock Off, it can't be countered by Ghosts or Psychics because of it, gets Drain Punch + Mach Punch, counters the really common Rotom-W + Gene core, Greninja, Goodra, etc it's seriously the best thing ever. The only thing it fears are Fairies like Clefable and Azuma (and they don't enjoy losing theirs items), Talonflame, Mega Venu and Pinsir. I'm sorry if someone answered this already, but have we gotten into it's sure-fire counters yet or those are basically it? What about the best EV spread for it? HP, Atk and Sp. Def?
Oh right, forgot Skarm! And I think the standard is Knock Off + Ice Punch, no? I mean it gets walled by Azuma, but that doesn't really matter. It can use Poison Jab for Clefable, Azuma, Togekiss (and Sylveon, yes, but Clefable is just better than it), and it's actually decent damage:Well, as far as counters go, I'm quite sure Skarmory can take it on, especially if Conkeldurr is not statused, as Brave Bird is actually a 2HKO. Intimidate users, like Arcanine or (lol) Granbull, can take it on fairly well, but I think that Conkeldurr is scarier on paper -- once you figure out his moveset (he's often lacking either Knock Off or one of the elemental punches), he becomes much easier to take care of. And among the fairies, you missed Sylveon, although it's quickly becoming irrelevant.
I prefer 252 HP / 252 Atk+ / 4 SDef simply because higher Drain Punch damage = more healing, but I believe 252 HP / 252 SpD+ is the more common spread. Assault Vest and 4 Special Defense EVs is nearly equivalent to Special Defense investment, so it makes more sense to me to have what's essentially a 252 HP / 252 Atk+ / 252 SpD+ spread.
Mega-Venusaur is best at switching into Conkeldurr, especially Giga Drain variants as Sludge Bomb could potentially activate Guts. Switched into Ice Punch before Mega evolving? Big deal, it's just 40% max. Just Synthesis and heal right back up to tank them again.Mega Heracross is probably the best at switching into conk, with terric physical bulk, resistance to fighting and dark and immunity to knock off's effect. On the other hand, EQ is the best think it can do in retaliation unless your're seriously going to use aerial ace.
Hera's also decidedly unpopular.
Pinser has a 4x fight resist and a stab that destroys conk. It is also immune to knock off's effect and is a very good poke in general. Unfortunately it is destroyed by ice punch or stone edge and doesn't resist knock off
Conkeldurr is, by far, the best user of this thing. Nothing likes to switch into Knock Off, it can't be countered by Ghosts or Psychics because of it, gets Drain Punch + Mach Punch, counters the really common Rotom-W + Gene core, Greninja, Goodra, etc it's seriously the best thing ever. The only thing it fears are Fairies like Clefable and Azuma (and they don't enjoy losing theirs items), Talonflame, Mega Venu and Pinsir. I'm sorry if someone answered this already, but have we gotten into it's sure-fire counters yet or those are basically it? What about the best EV spread for it? HP, Atk and Sp. Def?
I was always thinking how an assault vest regircock would do. It has a decent HP and good 100 special defense. I've only been able to test it out on UU. Don't know how well it will work out in OU.
252 SpA Mega Charizard Y Fire Blast vs. 252 HP / 4 SpD Assault Vest Regirock in Sun: 105-123 (28.8 - 33.7%) -- 0.9% chance to 3HKO
252 SpA Mega Charizard Y Solar Beam vs. 252 HP / 4 SpD Assault Vest Regirock: 204-240 (56 - 65.9%) -- guaranteed 2HKO
0- Atk Mega Charizard Y Earthquake vs. 252 HP / 0+ Def Regirock: 68-80 (18.6 - 21.9%) -- possible 5HKO
With no Stealth Rock even the highest damage rolls don't cut it, meaning Regirock can switch into a Fire Blast and take the SolarBeam as well. And this is simply with max HP. So AV Regirock performs admirably against certain targets. It's a dud against tough walls however, even with Adamant and max Attack EVs, which I recommend. Either that or Impish with mac Attack. He's still preferred to be used with sand support however, where you get some scary numbers.
252 SpA Mega Manectric Thunderbolt vs. 252 HP / 4 SpD Assault Vest Regirock in Sand: 67-81 (18.4 - 22.2%) -- possible 5HKO
-1 252 Atk Regirock Earthquake vs. 0 HP / 0 Def Mega Manectric: 146-174 (51.9 - 61.9%) -- guaranteed 2HKO after sandstorm damage
Assuming you took Intimidate its still a clean 2HKO. It has Clear Body though, which is better than Sturdy for reasons like this.
+1 252 SpA Clefable Moonblast vs. 252 HP / 4 SpD Assault Vest Regirock in Sand: 84-99 (23 - 27.1%) -- 50.3% chance to 4HKO
252 Atk Regirock Stone Edge vs. 252 HP / 0 Def Clefable: 178-210 (45.1 - 53.2%) -- 0.4% chance to 2HKO after Leftovers recovery
Say there's a Calm Mind boosting Clefable. It'd have to boost significantly to do sufficient damage.
+2 252+ Atk Aegislash-Blade Iron Head vs. 252 HP / 0+ Def Regirock: 314-372 (86.2 - 102.1%) -- 12.5% chance to OHKO
+2 252+ Atk Aegislash-Blade Sacred Sword vs. 252 HP / 0+ Def Regirock: 238-280 (65.3 - 76.9%) -- guaranteed 2HKO
252+ SpA Aegislash-Blade Shadow Ball vs. 252 HP / 4 SpD Assault Vest Regirock in Sand: 72-85 (19.7 - 23.3%) -- possible 5HKO
252 Atk Regirock Earthquake vs. 252 HP / 0 Def Aegislash-Blade: 316-372 (97.5 - 114.8%) -- 81.3% chance to OHKO
Regirock is slower than Aegeslash, so +2 Iron Head will likely just barely not kill you while Earthquake will always kill with Stealth Rock out. Autotomize versions do a pittance with Shadow Ball.
4 SpA Rotom-W Hydro Pump vs. 252 HP / 4 SpD Assault Vest Regirock in Sand: 110-132 (30.2 - 36.2%) -- 41.9% chance to 3HKO
4 SpA Rotom-W Volt Switch vs. 252 HP / 4 SpD Assault Vest Regirock in Sand: 36-43 (9.8 - 11.8%) -- possible 9HKO
252 Atk Regirock Stone Edge vs. 252 HP / 0 Def Rotom-W: 129-153 (42.4 - 50.3%) -- 0.4% chance to 2HKO after sandstorm damage and Leftovers recovery
Not an ideal matchup, but it shows that Regirock is capable of taking on weakened Rotom-W that are ballsy enough to go for the Hydro Pump. If they were wise, they'd burn instead. Regardless if you know a Volt Switch is coming, Regi tanks it nicely.
252 SpA Life Orb Protean Greninja Ice Beam vs. 252 HP / 4 SpD Assault Vest Regirock in Sand: 74-87 (20.3 - 23.9%) -- guaranteed 5HKO
252 SpA Life Orb Greninja Hydro Pump vs. 252 HP / 4 SpD Assault Vest Regirock in Sand: 174-211 (47.8 - 57.9%) -- 92.6% chance to 2HKO
252 Atk Regirock Drain Punch vs. 4 HP / 0 Def Greninja: 190-224 (66.4 - 78.3%) -- guaranteed 2HKO after sandstorm damage
252 Atk Regirock Stone Edge vs. 4 HP / 0 Def Greninja: 189-223 (66 - 77.9%) -- guaranteed 2HKO after sandstorm damage
In the sand, Regi can handedly take the Ice Beam if its threatening a Dragon as well as the following Hydro Pump if they stay in and don't U-Turn. The Drain Punch calc is if Greninja is a Dark or Ice type however, which he won't be when he uses Hydro Pump. Between the Sand and Life Orb damage however, two Drain Punches will take him out and keep you standing. Not the best matchup overall however.
252+ Atk Choice Band Talonflame Brave Bird vs. 252 HP / 0+ Def Regirock: 58-69 (15.9 - 18.9%) -- possible 6HKO
252+ Atk Choice Band Talonflame U-turn vs. 252 HP / 0+ Def Regirock: 45-54 (12.3 - 14.8%) -- possible 7HKO
Those are my favorite numbers though.
252 SpA Heatran Lava Plume vs. 252 HP / 4 SpD Assault Vest Regirock in Sand: 29-35 (7.9 - 9.6%) -- possibly the worst move ever
252 SpA Heatran Earth Power vs. 252 HP / 4 SpD Assault Vest Regirock in Sand: 90-106 (24.7 - 29.1%) -- 99.9% chance to 4HKO
252 Atk Regirock Earthquake vs. 252 HP / 0 Def Heatran: 348-412 (90.1 - 106.7%) -- 37.5% chance to OHKO
Great Heatran switch in. Even if you get burned you can still 2HKO it.
252+ Atk Life Orb Adaptability Crawdaunt Crabhammer vs. 252 HP / 0+ Def Regirock: 291-348 (79.9 - 95.6%) -- guaranteed 2HKO
252+ Atk Choice Band Adaptability Crawdaunt Aqua Jet vs. 252 HP / 0+ Def Regirock: 136-164 (37.3 - 45%) -- guaranteed 3HKO
252 Atk Regirock Superpower vs. 4 HP / 0 Def Crawdaunt: 250-296 (93.2 - 110.4%) -- 62.5% chance to OHKO
Ok, can I just say I am effing astounded that this guy with 0 Defense investment can always survive a Life Orb super effective Crawdaunt Adaptability Crabhammer? And Choice Band Aqua Jet is a 3HKO! That means you can switch into that and still potentially kill with Superpower.
252+ Atk Choice Band Entei Sacred Fire vs. 252 HP / 0+ Def Regirock: 60-72 (16.4 - 19.7%) -- guaranteed 4HKO after burn damage
252+ Atk Choice Band Entei Iron Head vs. 252 HP / 0+ Def Regirock: 130-154 (35.7 - 42.3%) -- guaranteed 3HKO after burn damage
252 Atk burned Regirock Stone Edge vs. 4 HP / 0 Def Entei: 156-184 (41.9 - 49.4%) -- guaranteed 2HKO after Stealth Rock and sandstorm damage
I threw on the burn for kicks. Entei doesn't even carry Iron Head (it carries Bulldoze), so this is an even worse matchup for him.
+2 252 Atk Tough Claws Mega Charizard X Flare Blitz vs. 252 HP / 0+ Def Regirock: 126-148 (34.6 - 40.6%) -- guaranteed 3HKO
+2 252 Atk Tough Claws Mega Charizard X Dragon Claw vs. 252 HP / 0+ Def Regirock: 168-198 (46.1 - 54.3%) -- 53.1% chance to 2HKO
252 Atk Regirock Stone Edge vs. 4 HP / 0 Def Mega Charizard X: 252-296 (84.5 - 99.3%) -- guaranteed 2HKO
Again, no Df investment and +2 Char X can't even reliably 2HKO. Any prior damage and its gone from Stone Edge.
+2 252 Atk Mega Pinsir Earthquake vs. 252 HP / 0+ Def Regirock: 246-290 (67.5 - 79.6%) -- guaranteed 2HKO
252 Atk Regirock Stone Edge vs. 4 HP / 0 Def Mega Pinsir: 472-556 (173.5 - 204.4%) -- guaranteed OHKO
Awesome.
252+ Atk Choice Band Technician Scizor Bullet Punch vs. 252 HP / 0+ Def Regirock: 162-192 (44.5 - 52.7%) -- 19.1% chance to 2HKO
252 Atk Regirock Fire Punch vs. 252 HP / 0 Def Scizor: 272-324 (79 - 94.1%) -- guaranteed 2HKO
252+ Atk Regirock Fire Punch vs. 252 HP / 0 Def Scizor: 300-356 (87.2 - 103.4%) -- 93.8% chance to OHKO after Stealth Rock
Also awesome.
So those are some examples of AV Regirock. The important thing is to pick your battles. Stay the hell away from bulky Ground and Water types. Unless you have Ice Punch and they are 4x weak, then you're ironically a decent Landorus-T check.
252+ Atk Landorus-T Earthquake vs. 252 HP / 0+ Def Regirock: 192-228 (52.7 - 62.6%) -- guaranteed 2HKO
252 Atk Regirock Ice Punch vs. 252 HP / 0 Def Landorus-T: 300-356 (78.5 - 93.1%) -- guaranteed 2HKO after Leftovers recovery
Because of Clear Body you don't fear Intimidate, and actually, this is a pretty damn good answer to the fearsome core that is Mega Manectric and Landorus-T.
0 Atk Gliscor Earthquake vs. 252 HP / 0+ Def Regirock: 102-122 (28 - 33.5%) -- 0.2% chance to 3HKO
252 Atk Regirock Ice Punch vs. 252 HP / 184+ Def Gliscor: 180-212 (50.8 - 59.8%) -- guaranteed 2HKO
Hell you're safe from Gliscor too with that move.
But again, know your limits and don't pretend with Assault Vest on that you're invincible. Use good prediction and use your good defenses on both sides to confound their expectations. It really depends on your moves. Drain Punch is good for longevity, but in all honestly you might benefit more from Superpower, Fire Punch and Ice Punch to really nail certain 4x weaknesses. No STAB on Drain Punch with only 100 base Attack isn't impressive, and you'd need Power-Up Punch to boost it, which hampers coverage and takes time you likely don't have. But it's not unreasonable to rely on a Latias or Sylveon for Wish and status healing.
If it switches into solarbeam its 2hkoed, if it switches into focus blast its 2hkoed, if it switches into fire blast all it needs is 10% of prior damage and its 2hkoed. Thats not a check, its a fodder. Calm mind clefable is physically defensive and will laugh at regirock's pathetical attempts to damage, i dont even know who would use 0 defense on a calm mind user. Sd aegislash calcs are pointless, thats literally the worst set available, and the fact that regirock can actually lose to it is laughable. Life orb aegis is just straight 2hkoing with iron head without thinking. Rotom-W is just going to burn you, period, end of story. You need sand to actually stand a CHANCE at dealing with greninja which is just stupid. What are those crawdaunt calcs supposed to prove? You can literally come in on one move and youre still losing a significant part of your health (that you CANT recover) while crawdaunt is just going to switch out, and thats assuming you actually predict correctly in first place. Scizor and landorus are dealing over 50% to your health meaning you need to come in after they kill something at which point the opponent can simply choose to sack them in order to screw your health and now you lose one pokemon and had other being crippled. Gliscor is just going to toxic+sub+protect stall you lol. Who cares if it can tank entei's attacks, a lot of things can. The entire point of entei is to spread burns which regirock is not immune to. I'm not even going to comment on that genesect calc because it probably speaks for itself. Stop assuming 1vs1 scenarios to prove a point, all of this just proves that regirock cant really come in on anything because of how much health it loses by doing so which makes it impossible for it to check any other threat. Conkeldurr can recover its own health with a powerful stab move coming out of 140 attack, provides support with knock off and doesnt need to be paired with stuff that share the same weakness as it to be usable, thats why its such a great assault vest user. Regirock is weak, cant provide any support, is over reliant on a limited weather condition and has a terrible typing.252 SpA Mega Charizard Y Fire Blast vs. 252 HP / 4 SpD Assault Vest Regirock in Sun: 105-123 (28.8 - 33.7%) -- 0.9% chance to 3HKO
252 SpA Mega Charizard Y Solar Beam vs. 252 HP / 4 SpD Assault Vest Regirock: 204-240 (56 - 65.9%) -- guaranteed 2HKO
0- Atk Mega Charizard Y Earthquake vs. 252 HP / 0+ Def Regirock: 68-80 (18.6 - 21.9%) -- possible 5HKO
With no Stealth Rock even the highest damage rolls don't cut it, meaning Regirock can switch into a Fire Blast and take the SolarBeam as well. And this is simply with max HP. So AV Regirock performs admirably against certain targets. It's a dud against tough walls however, even with Adamant and max Attack EVs, which I recommend. Either that or Impish with mac Attack. He's still preferred to be used with sand support however, where you get some scary numbers.
252 SpA Mega Manectric Thunderbolt vs. 252 HP / 4 SpD Assault Vest Regirock in Sand: 67-81 (18.4 - 22.2%) -- possible 5HKO
-1 252 Atk Regirock Earthquake vs. 0 HP / 0 Def Mega Manectric: 146-174 (51.9 - 61.9%) -- guaranteed 2HKO after sandstorm damage
Assuming you took Intimidate its still a clean 2HKO. It has Clear Body though, which is better than Sturdy for reasons like this.
+1 252 SpA Clefable Moonblast vs. 252 HP / 4 SpD Assault Vest Regirock in Sand: 84-99 (23 - 27.1%) -- 50.3% chance to 4HKO
252 Atk Regirock Stone Edge vs. 252 HP / 0 Def Clefable: 178-210 (45.1 - 53.2%) -- 0.4% chance to 2HKO after Leftovers recovery
Say there's a Calm Mind boosting Clefable. It'd have to boost significantly to do sufficient damage.
+2 252+ Atk Aegislash-Blade Iron Head vs. 252 HP / 0+ Def Regirock: 314-372 (86.2 - 102.1%) -- 12.5% chance to OHKO
+2 252+ Atk Aegislash-Blade Sacred Sword vs. 252 HP / 0+ Def Regirock: 238-280 (65.3 - 76.9%) -- guaranteed 2HKO
252+ SpA Aegislash-Blade Shadow Ball vs. 252 HP / 4 SpD Assault Vest Regirock in Sand: 72-85 (19.7 - 23.3%) -- possible 5HKO
252 Atk Regirock Earthquake vs. 252 HP / 0 Def Aegislash-Blade: 316-372 (97.5 - 114.8%) -- 81.3% chance to OHKO
Regirock is slower than Aegeslash, so +2 Iron Head will likely just barely not kill you while Earthquake will always kill with Stealth Rock out. Autotomize versions do a pittance with Shadow Ball.
4 SpA Rotom-W Hydro Pump vs. 252 HP / 4 SpD Assault Vest Regirock in Sand: 110-132 (30.2 - 36.2%) -- 41.9% chance to 3HKO
4 SpA Rotom-W Volt Switch vs. 252 HP / 4 SpD Assault Vest Regirock in Sand: 36-43 (9.8 - 11.8%) -- possible 9HKO
252 Atk Regirock Stone Edge vs. 252 HP / 0 Def Rotom-W: 129-153 (42.4 - 50.3%) -- 0.4% chance to 2HKO after sandstorm damage and Leftovers recovery
Not an ideal matchup, but it shows that Regirock is capable of taking on weakened Rotom-W that are ballsy enough to go for the Hydro Pump. If they were wise, they'd burn instead. Regardless if you know a Volt Switch is coming, Regi tanks it nicely.
252 SpA Life Orb Protean Greninja Ice Beam vs. 252 HP / 4 SpD Assault Vest Regirock in Sand: 74-87 (20.3 - 23.9%) -- guaranteed 5HKO
252 SpA Life Orb Greninja Hydro Pump vs. 252 HP / 4 SpD Assault Vest Regirock in Sand: 174-211 (47.8 - 57.9%) -- 92.6% chance to 2HKO
252 Atk Regirock Drain Punch vs. 4 HP / 0 Def Greninja: 190-224 (66.4 - 78.3%) -- guaranteed 2HKO after sandstorm damage
252 Atk Regirock Stone Edge vs. 4 HP / 0 Def Greninja: 189-223 (66 - 77.9%) -- guaranteed 2HKO after sandstorm damage
In the sand, Regi can handedly take the Ice Beam if its threatening a Dragon as well as the following Hydro Pump if they stay in and don't U-Turn. The Drain Punch calc is if Greninja is a Dark or Ice type however, which he won't be when he uses Hydro Pump. Between the Sand and Life Orb damage however, two Drain Punches will take him out and keep you standing. Not the best matchup overall however.
252+ Atk Choice Band Talonflame Brave Bird vs. 252 HP / 0+ Def Regirock: 58-69 (15.9 - 18.9%) -- possible 6HKO
252+ Atk Choice Band Talonflame U-turn vs. 252 HP / 0+ Def Regirock: 45-54 (12.3 - 14.8%) -- possible 7HKO
Those are my favorite numbers though.
252 SpA Heatran Lava Plume vs. 252 HP / 4 SpD Assault Vest Regirock in Sand: 29-35 (7.9 - 9.6%) -- possibly the worst move ever
252 SpA Heatran Earth Power vs. 252 HP / 4 SpD Assault Vest Regirock in Sand: 90-106 (24.7 - 29.1%) -- 99.9% chance to 4HKO
252 Atk Regirock Earthquake vs. 252 HP / 0 Def Heatran: 348-412 (90.1 - 106.7%) -- 37.5% chance to OHKO
Great Heatran switch in. Even if you get burned you can still 2HKO it.
252+ Atk Life Orb Adaptability Crawdaunt Crabhammer vs. 252 HP / 0+ Def Regirock: 291-348 (79.9 - 95.6%) -- guaranteed 2HKO
252+ Atk Choice Band Adaptability Crawdaunt Aqua Jet vs. 252 HP / 0+ Def Regirock: 136-164 (37.3 - 45%) -- guaranteed 3HKO
252 Atk Regirock Superpower vs. 4 HP / 0 Def Crawdaunt: 250-296 (93.2 - 110.4%) -- 62.5% chance to OHKO
Ok, can I just say I am effing astounded that this guy with 0 Defense investment can always survive a Life Orb super effective Crawdaunt Adaptability Crabhammer? And Choice Band Aqua Jet is a 3HKO! That means you can switch into that and still potentially kill with Superpower.
252+ Atk Choice Band Entei Sacred Fire vs. 252 HP / 0+ Def Regirock: 60-72 (16.4 - 19.7%) -- guaranteed 4HKO after burn damage
252+ Atk Choice Band Entei Iron Head vs. 252 HP / 0+ Def Regirock: 130-154 (35.7 - 42.3%) -- guaranteed 3HKO after burn damage
252 Atk burned Regirock Stone Edge vs. 4 HP / 0 Def Entei: 156-184 (41.9 - 49.4%) -- guaranteed 2HKO after Stealth Rock and sandstorm damage
I threw on the burn for kicks. Entei doesn't even carry Iron Head (it carries Bulldoze), so this is an even worse matchup for him.
+2 252 Atk Tough Claws Mega Charizard X Flare Blitz vs. 252 HP / 0+ Def Regirock: 126-148 (34.6 - 40.6%) -- guaranteed 3HKO
+2 252 Atk Tough Claws Mega Charizard X Dragon Claw vs. 252 HP / 0+ Def Regirock: 168-198 (46.1 - 54.3%) -- 53.1% chance to 2HKO
252 Atk Regirock Stone Edge vs. 4 HP / 0 Def Mega Charizard X: 252-296 (84.5 - 99.3%) -- guaranteed 2HKO
Again, no Df investment and +2 Char X can't even reliably 2HKO. Any prior damage and its gone from Stone Edge.
+2 252 Atk Mega Pinsir Earthquake vs. 252 HP / 0+ Def Regirock: 246-290 (67.5 - 79.6%) -- guaranteed 2HKO
252 Atk Regirock Stone Edge vs. 4 HP / 0 Def Mega Pinsir: 472-556 (173.5 - 204.4%) -- guaranteed OHKO
Awesome.
252+ Atk Choice Band Technician Scizor Bullet Punch vs. 252 HP / 0+ Def Regirock: 162-192 (44.5 - 52.7%) -- 19.1% chance to 2HKO
252 Atk Regirock Fire Punch vs. 252 HP / 0 Def Scizor: 272-324 (79 - 94.1%) -- guaranteed 2HKO
252+ Atk Regirock Fire Punch vs. 252 HP / 0 Def Scizor: 300-356 (87.2 - 103.4%) -- 93.8% chance to OHKO after Stealth Rock
Also awesome.
So those are some examples of AV Regirock. The important thing is to pick your battles. Stay the hell away from bulky Ground and Water types. Unless you have Ice Punch and they are 4x weak, then you're ironically a decent Landorus-T check.
252+ Atk Landorus-T Earthquake vs. 252 HP / 0+ Def Regirock: 192-228 (52.7 - 62.6%) -- guaranteed 2HKO
252 Atk Regirock Ice Punch vs. 252 HP / 0 Def Landorus-T: 300-356 (78.5 - 93.1%) -- guaranteed 2HKO after Leftovers recovery
Because of Clear Body you don't fear Intimidate, and actually, this is a pretty damn good answer to the fearsome core that is Mega Manectric and Landorus-T.
0 Atk Gliscor Earthquake vs. 252 HP / 0+ Def Regirock: 102-122 (28 - 33.5%) -- 0.2% chance to 3HKO
252 Atk Regirock Ice Punch vs. 252 HP / 184+ Def Gliscor: 180-212 (50.8 - 59.8%) -- guaranteed 2HKO
Hell you're safe from Gliscor too with that move.
But again, know your limits and don't pretend with Assault Vest on that you're invincible. Use good prediction and use your good defenses on both sides to confound their expectations. It really depends on your moves. Drain Punch is good for longevity, but in all honestly you might benefit more from Superpower, Fire Punch and Ice Punch to really nail certain 4x weaknesses. No STAB on Drain Punch with only 100 base Attack isn't impressive, and you'd need Power-Up Punch to boost it, which hampers coverage and takes time you likely don't have. But it's not unreasonable to rely on a Latias or Sylveon for Wish and status healing.
EDIT: One more.
+1 252 SpA Genesect Thunderbolt vs. 252 HP / 4 SpD Assault Vest Regirock: 93-110 (25.5 - 30.2%) -- guaranteed 4HKO
252 Atk Genesect Iron Head vs. 252 HP / 0+ Def Regirock: 122-146 (33.5 - 40.1%) -- guaranteed 3HKO
252 Atk Regirock Fire Punch vs. 0 HP / 0 Def Genesect: 288-340 (101.7 - 120.1%) -- guaranteed OHKO
Not bad right?
If it switches into solarbeam its 2hkoed, if it switches into focus blast its 2hkoed, if it switches into fire blast all it needs is 10% of prior damage and its 2hkoed. Thats not a check, its a fodder. Calm mind clefable is physically defensive and will laugh at regirock's pathetical attempts to damage, i dont even know who would use 0 defense on a calm mind user. Sd aegislash calcs are pointless, thats literally the worst set available, and the fact that regirock can actually lose to it is laughable. Life orb aegis is just straight 2hkoing with iron head without thinking. Rotom-W is just going to burn you, period, end of story. You need sand to actually stand a CHANCE at dealing with greninja which is just stupid. What are those crawdaunt calcs supposed to prove? You can literally come in on one move and youre still losing a significant part of your health (that you CANT recover) while crawdaunt is just going to switch out, and thats assuming you actually predict correctly in first place. Scizor and landorus are dealing over 50% to your health meaning you need to come in after they kill something at which point the opponent can simply choose to sack them in order to screw your health and now you lose one pokemon and had other being crippled. Gliscor is just going to toxic+sub+protect stall you lol. Who cares if it can tank entei's attacks, a lot of things can. The entire point of entei is to spread burns which regirock is not immune to. I'm not even going to comment on that genesect calc because it probably speaks for itself. Stop assuming 1vs1 scenarios to prove a point, all of this just proves that regirock cant really come in on anything because of how much health it loses by doing so which makes it impossible for it to check any other threat. Conkeldurr can recover its own health with a powerful stab move coming out of 140 attack, provides support with knock off and doesnt need to be paired with stuff that share the same weakness as it to be usable, thats why its such a great assault vest user. Regirock is weak, cant provide any support, is over reliant on a limited weather condition and has a terrible typing.
Easy there buddy.
252+ Atk Landorus-T Earthquake vs. 252 HP / 0 Def Conkeldurr: 204-240 (49.2 - 57.9%) -- 96.9% chance to 2HKO
-1 252+ Atk Conkeldurr Ice Punch vs. 252 HP / 0 Def Landorus-T: 276-328 (72.2 - 85.8%) -- guaranteed 2HKO after Leftovers recovery
252 SpA Mega Charizard Y Fire Blast vs. 252 HP / 4 SpD Assault Vest Conkeldurr in Sun: 297-351 (71.7 - 84.7%) -- guaranteed 2HKO
252+ Atk Conkeldurr Drain Punch vs. 4 HP / 0 Def Mega Charizard Y: 87-103 (29.1 - 34.5%) -- 7.3% chance to 3HKO
252+ Atk Conkeldurr Thunder Punch vs. 4 HP / 0 Def Mega Charizard Y: 234-276 (78.5 - 92.6%) -- guaranteed 2HKO
+2 252 Atk Tough Claws Mega Charizard X Flare Blitz vs. 252 HP / 0 Def Conkeldurr: 532-627 (128.5 - 151.4%) -- guaranteed OHKO
+2 252 Atk Tough Claws Mega Charizard X Dragon Claw vs. 252 HP / 0 Def Conkeldurr: 355-418 (85.7 - 100.9%) -- 12.5% chance to OHKO
252 SpA Life Orb Greninja Hydro Pump vs. 252 HP / 4 SpD Assault Vest Conkeldurr: 187-222 (45.1 - 53.6%) -- 38.3% chance to 2HKO (Yes, Drain Punch and Mach Punch wins but the point is Conk cant switch in and take two either)
I don't mind if you say Regirock isn't amazing or that Conkeldurr is better, which he is, but at least be fair and hold them up to the same standards and point out the instances where Regirock does indeed fair better. So thanks for glossing over all of his positive matchups, because I fail to see how being great against Char X, Talonflame, Volcarona, Mega Pinsir and Genesect isn't a fair niche. In the worst case scenario, Char Y beats Regi with amazing Solarbeam prediction, or has to hit twice with Focus Blast. But he at least CAN win. Conk can never switch in and can only do nominal damage if he's carrying the unlikely Thunder Punch. Even with Guts, Conk can be Toxic stalled too needing to get past the Sub. He's also 2HKO by Landorus and susceptible to Intimidate. The Crawdaunt calc was to show the bulk when even super effective, who can still potentially retaliate. And what does "probably speaks for itself" exactly mean anyway referring to genesect? Regirock fears none of Genesects +1 beam coverage nor U-Turn and Iron Head can never 2HKO. How is that not relevant? Scizor isn't always doing over 50%, if you read it only has a 20% chance to 2HKO, be fair. And with AV, sand only reduces special damage by roughly 10% of his HP overall, he's functional without it, but certain matchups want sand yes. And Rock isn't horrible when you have resistances to Fire and Flying, two of the most prevalent attack types, and STAB Stone Edge, one of the best offensive types in the game. Pure Fighting is no marvel defensively, good for U-Turn and Stealth Rock primarily.
Conk does have amazing Attack, Guts, Drain Punch, Mach Punch and Knock Off. He's amazing and pretty much unequivocally the best AV user. I could easily list a ton of favorable matchups for him that Regi can't muster. I agree with the points you're arguing but at least argue fairly and concede to valid match ups. No, I don't recommend Regi over Conk. No, I don't even really recommend him for OU. But is he a good candidate for the item?
Yes.