New nomination: Pineco to C tier
So this is kind of controversial because Pineco sucks shit. Like, it's total dogass. Unusably so. But. Turns out Forretress is pretty damn good!
If you grind Pineco (or are smart and use the day care) you end up with a dude who hits decently hard, outspeeds a surprising amount of stuff, and hard walls about 55% of the game. Bug Bite gives you decent stab options and your usual Normal/Dark (Strength/Payback) let's you hit stuff neutrallly. Sorry will usually 2/3hko stuff but opponent's will usually 6-7hko when they deign to attack so you're Gucci there.
Sorry has good matchups against Pryce and Claire, and absolutely trashes Rival especially if you choose meganium. It also wrecks team rocket which is especially useful when you need to tank explosions from various weezing/electrode. Great matchup vs Koga, good matchup vs Will and Karen, and can contribute vs Lance
FORRY is good Mon, much better than I'd have ever guessed