I'd say Scorbunny should be AT LEAST B, with continuing discussions for him to go up further. I've played probably 150-200 ladder games in the past days with Choice Scarf Scorbunny in 1500+ ELO, and have found that Scorbunny poses a massive threat. Like a massive one. Libero makes even the casual pivot U-Turn into 50% off of your Staryu. Is he about to Blaze Kick or HJK and 2-Shot my switch in? Does it have sucker? Gunk Shot is great coverage, etc. etc.Why is scorbunny unranked? Sure, mienfoo is practically just it but better, but gunk shot is really nice for fairies such as galarian ponyta and spritzee. Also, with sucker punch it can stop digletts with light chip from easily revenging it, and it has the added benefit of destroying foongus. All in all, I think scorbunny deserves C- or C. I don't have any replays, but if they are really necessary then I'll get some
In the later stages of a game, Scorbunny serves as a win condition who is the fastest mon in the match and can easily clean up a weakened team. After some Knock Offs and Stealth Rock chip goes around, HJK/Blaze Kick/Gunk Shot is most likely able to at least put a huge hole in the opponents team.
Early/mid game, Scorbunny can serve as a counter to a lot of mons. For example, when people bring in Scraggy, they instantly tend to D-Dance (most don't HJK/Knock, but some do, and it doesn't one shot Scorbunny). Switching to Scorbunny on the DD is free, and either the opponent doesn't expect the Scarf HJK or you get a strong U-Turn that nets you some momentum/predict a switch and get a kill.
Obviously, LO Abra gets revenge killed, and sash Bra gets his sash popped by U-Turn and his move walled by the appropriate switch-in.
Grassy Seed SD Grookey gets revenge killed by Blaze Kick after rocks (Scorbunny lives a +2 GG at Max HP and kills +1 Def Grookey after some chip).
LOrb Grookey is threatened to be revenge killed to, so has to switch out every time. Remember, every time a Pokemon switches out with a Scorbunny in its face, you have to handle:
STAB Gunk Shot
STAB Blaze Kick
and if the Scorbunny player doesn't really feel like dropping one of these, he can opt for the safe STAB U-Turn and gain some solid momentum, saving the bunny for another turn.
Evio Frillish and Mareanie are the most reliable switch ins to a Scorbunny, but they don't pose much of a threat when they switch in. Whether Scorbunny U-Turns or not, Frillish and Mareanie are easily walled (Mareanie also easily trapped if the opponent isn't careful).
Koffing is also a really good switch in, but once he gets knocked off, he:
1. Can't Will-O a Scorb, so has to be careful for the switch-in on a WoW
2. Takes a good chunk from Blaze Kick and HJK
So the Koffing player has to be very careful he can handle Scorbunny once his Koffing suddenly dies, 'cause an evio-less Koffing doesn't last long vs. Scorbunny.
Scarf Scorbunny can't be trapped by Diglett unless Scorb is low-HP, or if the Diglett is sashed and the Scorb can't U-Turn. Every move except Gunk Shot either switches Bunny out or one shots digletts.
Evio Staryu is 2HKO'd by HJK, but a scarf Staryu or *one that rapid spins* (much more common and much more of an issue) anticipating your Scorbunny's ability to clean up pose as problems for a Scorbunny looking to sweep.
The threat and tempo Scorbunny provides is kind of unmatched in the tier, probably only by Foo. Paired with a pivot Foo, Scorbunny can just absolutely wreak havoc. Taunt Foo can prevent rocks on turn 1, spread knocks around all game (most importantly, get the evio off an opposing mienfoo turn 1! thats massive cause it allows scorbunny HJK to one shot at 80%), does insane damage with HJK and spreads chip with U-Turn.
I know that this post is about Scorbunny but Mienfoo compliments him so well and can't go unmentioned. Diglett is an honorable mention. These two mons punch holes into your opponents team that make it super easy for BJ/Scarf Scorbunny to clean up late game, and really highlight his strengths.
So yeah, Scorbunny is really strong and it would be plain wrong to have him lower than B (imo). The threat of all the STAB Moves and the momentum given by U-Turn is great. The uncertainty between BJ and Scarf is valuable, as both items are very viable on Scorbunny. BJ Scorbunny doesn't have the problem of being locked into moves, so if a scarfer isn't needed, Scorbunny could serve as a threat with a wide spread of coverage (but at a contentious speed tier of 17).
Sadly don't have any replays but you guys can try out Scarf/BJ Scorbunny yourselves and see what he can do.
edit: realized a paragraph wasnt finished, finished it, added a little bit of extra details