Victini B+ -> B This is something the ranking team unanimously agrees on so it's probably going to happen no matter what, but I still wanted to warn you guys before it actually happens b/c it would be kinda shitty of us to just move Pokemon without any prior warning. Victini is really not that great in the current meta and really deserves to drop to B rank.
MixTini is actually a pretty decent wallbreaker and actually has a strong matchup vs standard stall, but it kinda sucks vs offensive teams and suffers from a bunch of obvious flaws like SR weakness, weakness to common types, Pursuit weakness, the speed drop caused by V-Create making it pretty easy to take advantage of, plus it doesn't get to many opportunities to attack vs most teams since it gets worn down so easily, overall it's not really a B+ set on its own, and the other sets really aren't enough to make it B+ material either. Band struggles a lot with all the Tankchomps running around and its main STAB has really common resistances. Wisp+Taunt's lack of recovery and SR weakness prevents it from consistently checking stuff like Gardevoir and YZard, and it's a pretty niche set in general. Sub PuP and Scarf are kinda bad tbh, Sub PuP is Chomp food, and Scarf is just way too easy to wall and doesn't really check any sweepers (loses to XZard, loses to Altaria, loses to Sand Rush Exca), so there's little reason to run it over other scarfers. Its status as a Fairy check is a lot less valid nowadays, Clefable runs TWave, Altaria runs EQ, Diancie is Diancie, it only really checks Garde which still does a lot w/ Hyper Voice. Not a bad Pokemon by any means, but it's just not on par with the rest of B+ rank.
Now for my own nomination:
Cobalion C+ -> B- I brought this up a while ago, but now I've used this thing a lot more and I really think it deserves to move up. I've been experimentiong with different sets than the standard STABs/Rocks/Volt Switch, and I've been impressed by how well they've performed. For instance, I've been using a Sub SD set, and while it's kinda weak even after a Swords Dance, it does set up really easily, espeically against bulkier teams which use stuff like Ferrothorn and Sableye which are just food for Cobalion. Given that its checks are pretty prevalent it's not going to sweep most teams, but SD isn't really the point of the set anyway, it's more something it can use to break through bulkier teams if it needs to, and it does help from time to time. (
http://replay.pokemonshowdown.com/ou-292715459 http://replay.pokemonshowdown.com/ou-292715459 http://replay.pokemonshowdown.com/ou-292724877 http://replay.pokemonshowdown.com/ou-292779014 bunch of replays, some of then featuring Cobalion hadling things it's supposed to lose to quite well)
I've also used SubToxic, which I've actually found even better since it's a lot more consistent, it's rarely ever deaweight since it's almost always going to be able to poison something, like here for instance
http://replay.pokemonshowdown.com/ou-292806945, I only have one replay, but trust me, this kind of stuff happens pretty much every battle, though to a lesser extent. Really, the main impression I get from Cobalion is that, outside of Close Combat and Iron Head, it can run whatever combination of moves it wants, be it SR+Volt Switch, SR+Taunt, Sub+Taunt, Sub+SD, Sub+Toxic, Magnet Rise+Toxic, Magnet Rise+Taunt, Magnet Rise+SD, Stone Edge+SD, Stone Edge+Toxic, Volt Switch+Toxic, and so on. While it's always going to struggle against something, it's completely moveset dependant, there's no single thing that can take on every set comfortably, and as a result, it's very easy to screw over switchins, and pave the way for something else to sweep. It's a very flexible Pokemon which can perform different roles depending on what its team requires of it. It's just a solid support Pokemon in general, and it's defenitely on par with the rest of B- rank imo.