I'm glad this suspect test is finally happening. Although Weavile is very fragile and it rarely ever lives any attack, once it's out is guaranteed to:
1. Grab a KO on a mon weak to its stabs or anything chipped enough.
2. Pursuit trap/revenge kill with Ice Shard other offensive mons (also grabbing a very important KO).
3. At least disarm and heavily dent any incoming wall through Knock off.
With a choice band or life orb, pretty much nothing switches into it as previously stated. I feel that even though Weavile does have its shortcomings like being unable to break through a few dedicated walls (It will still cripple them with knock off) or sometimes not hitting hard enough with ice shard, compared to other fragile offensive pokemon like Terrakion, Infernape or Mega Beedrill it is too cheap and splashable on any team for it to remain in the tier.
Even if it is weak to rocks, UU has lots of defoggers and is the tier with the most viable rapid spinners. Weavile needs little to no team support to function and is a threat to every archtype.
In my frank opinion I believe Terrakion, Infernape, and Mega Beedrill are far more splashable because they aren't revenge killed as easily while providing the same punch that Weavile provides. Weavile's STAB attacks are good but STAB Knock Off is not good enough to consider it banworthy, which is one of the first things pointed out in the OP of this post. There are a lot of commonly used Pokemon which can take care of Weavile and revenge kill it most of all. While it's true that Weavile can easily revenge kill your Pokemon, Weavile itself is revenge killed easier than any other Pokemon in UnderUsed.
There are a number of Pokemon that can even take advantage of that. Crawdaunt and Infernape can set up Dragon Dance(SD is better on Crawdaunt IMO)/Swords Dance respectively when Weavile inevitably switches out. Magneton, Darmanitan, and Mienshao can pivot with Volt Switch and U-Turn to regain momentum. Klefki and Mega Aggron can set up Spikes and Stealth Rocks.
I would also like to point out that even if it is super fragile, is not fragile enough to be picked by a few notable moves:
252+ Atk Choice Band Entei Extreme Speed vs. 0 HP / 0 Def Weavile: 187-221 (66.5 - 78.6%) -- 31.3% chance to OHKO after Stealth Rock
Considering Forretress is one of the most common leads, Forretress can also set up Spikes, and SR+1 layer of Spikes is a guaranteed OHKO. Not to mention it's better to take the 31% chance of OHKOing than underspeeding and taking a lot of damage, potentially missing with Sacred Fire.
I personally agree though in that Entei isn't really a good Weavile check.
96+ Atk Metagross Bullet Punch vs. 0 HP / 0 Def Weavile: 188-224 (66.9 - 79.7%) -- 37.5% chance to OHKO after Stealth Rock
Metagross is used more with 252+ Attack.
+----------------------------------------+
| Spreads |
| Naive:0/4/0/252/0/252 17.426% |
| Adamant:0/252/0/0/4/252 11.246% |
| Jolly:0/252/4/0/0/252 9.394% |
| Adamant:252/252/0/0/4/0 9.021% |
| Adamant:236/96/0/0/0/176 8.032% |
| Adamant:0/252/4/0/0/252 7.389% |
| Other 37.491% |
http://www.smogon.com/stats/2017-08/moveset/gen7uu-1760.txt
Metagross also has a recommended Choice Band set as well, even though you're using the Shuca Berry set. Assault Vest and Life Orb are more common, however.
252 Atk Choice Band Adaptability Crawdaunt Aqua Jet vs. 0 HP / 0 Def Weavile: 176-208 (62.6 - 74%) -- guaranteed 2HKO after Stealth Rock
Swords Dance/Dragon Dance Crawdaunt is more common and actually does beat Weavile.
252 SpA Manectric-Mega Flamethrower vs. 0 HP / 4 SpD Weavile: 230-272 (81.8 - 96.7%) -- guaranteed OHKO after Stealth Rock
252+ Atk Sharpedo-Mega Waterfall vs. 0 HP / 0 Def Weavile: 216-255 (76.8 - 90.7%) -- guaranteed OHKO after Stealth Rock
Meanwhile you have Mega Beedrill taking your mega slot and dying to Entei even without rocks:
252+ Atk Choice Band Entei Extreme Speed vs. 0 HP / 4 Def Beedrill-Mega: 265-312 (97.7 - 115.1%) -- 87.5% chance to OHKO
Overall I feel Weavile grabs too much momentum, forces 50/50's and it cleans late game easily. It does too much for little cost and I wouldn't mind seeing it go.
I don't know where the Mega Beedrill reference came from, but Mega Beedrill vastly outspeeds threats that Weavile can't. Mega Beedrill will almost always switch out, just as Weavile would. Unlike Mega Beedrill, Weavile has a lot more checks and counters. Mega Beedrill isn't checked/countered based on it's bulk, it's checked/countered by virtue of it's average offensive typing which leaves it walled by physically defensive Rock and Steel types. Even Drill Run generally doesn't do much to the likes of Forretress or Mega Aggron. Weavile is a lot easier to outspeed and is weak to multiple priority moves.
There are a lot of bulky Water and Steel types which check/counter Weavile as well as high offensive Pokemon which can set up on Weavile or OHKO it with priority.
- Alomomola doesn't appreciate being Knocked Off, but on a Stall team it can just utilize Regenerator and Wish to get it's health back.
- If Weavile isn't running Low Kick, Cobalion can take both STABs of Weavile well and force it out in return. Cobalion can also pivot with Volt Switch to gain momentum.
- Crawdaunt sets up on it and beats it.
- Scarf Darmanitan revenge kills and can pivot.
- Scarf Heracross revenge kills it.
- Scarf Magneton outspeeds and can OHKO it or pivot.
- Max Attack (Life Orb) Metagross OHKOs Weavile.
- Scarf Mienshao outspeeds and can OHKO it or pivot.
- Rotom-Wash can take a hit and burn it or pivot.
- Scizor can OHKO it with Bullet Punch.
- Volcanion has good enough bulk that it can take a hit from Weavile and OHKO it in return. Z move variants take reduced damage from Knock Off and completely counter Weavile.
- Scarf Terrakion can revenge kill it, and non-Scarf variants can take a hit and OHKO it.
- Mega Aggron counters it by walling it entirely. Mega Aggron can set up Rocks, or in the rare scenario that you're running Curse, then Aggron can set up Curse boosts.
- Mega Blastoise has decent 79/120 bulk and can't have it's Mega Stone knocked off. Mega Blastoise is 3HKOd by Knock Off, so it counters Weavile.
- Forretress, despite generally being a lead, can still switch in as it has reasonably good physical Defense and also has access to Gyro Ball which OHKOs Weavile or Volt Switch which is used to Pivot.
- Infernape can OHKO Weavile with Mach Punch or set up a Swords Dance boost to potentially sweep the enemy team.
- Klefki can set up dualscreens, Spikes, and both of it's STABs can OHKO Weavile.
- Mega Manectric outspeeds and has Intimidate. Mega Manectric also OHKOs Weavile.
- Primarina has decent bulk which lets it take a hit from Weavile and hit it back with Moonblast.
- Mega Sharpedo outspeeds and OHKOs Weavile after Rocks.
- God forbid you use Arcanine, it has Intimidate, Will-O-Wisp, and Morning Sun which let it completely counter Weavile.
Personally, I'd argue that there are an awful lot of checks and counters to Weavile, and I don't believe strength and speed alone warrant a ban for Weavile, regardless of how good it's STAB combo may be. This list consists of a lot of UnderUsed Pokemon, and I don't reasonably see people not having at least one or two of these Pokemon on their teams, even if Weavile can get residual damage on one of it's would-be checks.