They don't overprep for Ash-Gren. No one has given an example of what "overprepping for Gren" even looks like. All the mons that wall it in OU would have usage with or without its presence. Dudes like Ferrothorn, Pex, Fini, Bulu, Chansey, Tangrowth, Kommo-O are being used for plenty of other reasons than Greninja.The fact teams overprep for Ash-Greninja is a strong point for its stay in S. Because just because it isn‘t murdering everyone on the ladder doesn‘t mean it wouldn‘t murder on an equal playfield. If we‘re going by those rules Toxapex‘d need to drop as well and that‘s not going to happen.
Just to move things along though:
I think Vic is worthy of B+ nomination due to Choice Band & Choice Scarf sets. Choice Band is an unstoppable nuke and Choice Scarf is seeing increased usage due to Final Gambit. It also is a very good switch into all forms of Tapu Lele (offensive sets can once, but that's all Vic needs to claim a mon due to sheer power).
My other change would be Manaphy rising to B+ as well. Manaphy with HydraRest is the best rain abuser in the tier, period. However, it does require rain support to reach full potential. That's what stops it from being in the A ranks.
Other than those I think most things on the VR are accurately placed. Maybe Weavile being B is a stretch for me but I don't see it often enough to really have a developed opinion.