Klutz Regigigas is completely useless. No resistances or recovery to take advantage of that nice bulk, just good Speed so it doesn't fare great against offensive teams either, and very lacking in power due to lack of a good STAB and inability to use items. If you really want a bulky and powerful Normal-type just use Eviolite Analytic Porygon 2, which hits just as hard (hits harder when using coverage moves, but has less power when using STAB moves, but most of the time you will want to be using coverage moves anyway), is much bulkier, and has reliable recovery:
- 252 SpA Life Orb Latios Draco Meteor vs. 252 HP / 0 SpD Regigigas: 255-302 (60.1 - 71.2%) -- guaranteed 2HKO
- 252 SpA Life Orb Latios Draco Meteor vs. 252 HP / 0 SpD Eviolite Porygon2: 192-227 (51.3 - 60.6%) -- guaranteed 2HKO
I guess the extra Speed can be nice to outspeed some important Pokemon such as Mega Heracross, and a few others, but even then Regigigas doesn't have the power to OHKO Mega Heracross (61 - 72.3%), and is not hard at all to wall with almost any physical wall / pivot:
- 252+ Atk Regigigas Return vs. 252 HP / 252+ Def Hippowdon: 138-163 (32.8 - 38.8%) -- 5.5% chance to 3HKO after Leftovers recovery
- 252+ Atk Regigigas Fire Punch vs. 252 HP / 252+ Def Skarmory: 120-142 (35.9 - 42.5%) -- 94.6% chance to 3HKO after Leftovers recovery
- 252+ Atk Regigigas Superpower vs. 212 HP / 252 Def Solid Rock Rhyperior: 166-196 (39.1 - 46.2%) -- guaranteed 3HKO after Leftovers recovery
- 252+ Atk Regigigas Return vs. 252 HP / 252+ Def Mega Venusaur: 133-157 (36.5 - 43.1%) -- guaranteed 3HKO
- 252+ Atk Regigigas Return vs. 248 HP / 136+ Def Mandibuzz: 163-193 (38.5 - 45.6%) -- guaranteed 3HKO after Leftovers recovery
- 252+ Atk Regigigas Return vs. 252 HP / 252+ Def Slowbro: 144-171 (36.5 - 43.4%) -- 99.1% chance to 3HKO after Leftovers recovery
- 252+ Atk Regigigas Return vs. 36 HP / 220+ Def Alomomola: 183-216 (38.1 - 45%) -- guaranteed 3HKO after Stealth Rock and Leftovers recovery
- -1 252+ Atk Regigigas Ice Punch vs. 252 HP / 252+ Def Landorus-T: 220-260 (57.5 - 68%) -- guaranteed 2HKO after Leftovers recovery
And if you use Regigigas as a fast bulky attacker instead of a bulky tank, why not use Terrakion, Keldeo, or any of the other fast hard hitters that are more difficult to wall and provide actual resistances? To give you an example of how crippling the lack of item is, here is a comparison between Regigigas's and LO Terrakion's power:
- 252+ Atk Regigigas Return vs. 252 HP / 252+ Def Slowbro: 144-171 (36.5 - 43.4%) -- 99.1% chance to 3HKO after Leftovers recovery
- 252 Atk Life Orb Terrakion Stone Edge vs. 252 HP / 252+ Def Slowbro: 142-169 (36 - 42.8%) -- 96.4% chance to 3HKO after Leftovers recovery
So, Terrakion hits just as hard with its weaker STAB move, while being able to hit a ton of important Pokemon for super effective damage and help check Pokemon such as Heatran, Bisharp, and Mega Charizard Y with its resistances.
Baton Pass Sharpedo is not that interesting either, because it lacks bulk. For offensive Baton Pass users to be good partners to other offensive Pokemon they must either have good synergy with them or be able to boost their defenses (see Scolipede). When you don't even need to hit Sharpedo with a super effective move to take it out, you just can't pick the right partners to Baton Pass the boosts to, simply because anything that can take a hit from Sharpedo or has priority is a check.
Technician Mega Abomasnow is a very interesting idea though. A set of Ice Shard / Bullet Seed / Earthquake / Hidden Power Fire seems the best from a quick glance, with max Attack and some Speed to outrun some slow walls. Let's see some calcs:
- 252+ Atk Technician Mega Abomasnow Bullet Seed (3 hits) vs. 4 HP / 252+ Def Eviolite Chansey: 270-318 (42 - 49.5%) -- approx. 94.5% chance to 2HKO after Stealth Rock (If you get three hits with both attacks or 4-5 hits with the first attack you almost always take out Chansey after SR, and you can outspeed it with near maximum Speed investment)
- 252+ Atk Technician Mega Abomasnow Ice Shard vs. 0 HP / 4 Def Thundurus: 290-344 (96.9 - 115%) -- 87.5% chance to OHKO
- 252+ Atk Technician Mega Abomasnow Ice Shard vs. 4 HP / 0 Def Latios: 264-312 (87.4 - 103.3%) -- 93.8% chance to OHKO after Stealth Rock
- 16 SpA Technician Mega Abomasnow Hidden Power Fire vs. 248 HP / 100 SpD Mega Scizor: 304-360 (88.6 - 104.9%) -- guaranteed OHKO after Stealth Rock
- 16 SpA Technician Mega Abomasnow Hidden Power Fire vs. 252 HP / 168 SpD Ferrothorn: 256-304 (72.7 - 86.3%) -- guaranteed 2HKO after Stealth Rock and Leftovers recovery
- 16 SpA Technician Mega Abomasnow Hidden Power Fire vs. 252 HP / 4 SpD Skarmory: 222-262 (66.4 - 78.4%) -- guaranteed 2HKO after Leftovers recovery
- 252+ Atk Mega Abomasnow Earthquake vs. 248 HP / 4 Def Mega Charizard X: 222-262 (61.8 - 72.9%) -- guaranteed 2HKO. With SR up, EQ + Ice Shard 2HKOes
- 252+ Atk Technician Mega Abomasnow Ice Shard vs. 0 HP / 4 Def Mega Charizard Y: 135-159 (45.4 - 53.5%) -- 34.4% chance to 2HKO
- 252+ Atk Technician Mega Abomasnow Ice Shard vs. 248 HP / 136+ Def Mandibuzz: 168-200 (39.7 - 47.2%) -- 96.9% chance to 2HKO after Stealth Rock and Leftovers recovery
So, with just SR up nothing walls Mega Abomasnow except from Mega Venusaur and that strong Ice Shard is also immensely useful. Aboma can even go special to get past Mega Venusaur, thanks to a 135 BP Frost Breath before STAB, but Ice Shard + Bullet Seed are the real reasons to use Mega Aboma, so i don't think that going special is worth it.