MASSIVE CHANGES INCOMING
(Massive thanks to Ojama for helping me with this update)
Mamoswine up from B-rank ==> A-rank
Alakazam up from B-rank ==> A-rank
Volcarona up from B-rank ==> A-rank
Kyurem up from B-rank ==> A-rank
Tentacruel up from B-rank ==> A-rank
Mamoswine: I'm going to be honest, I avoided moving Mamoswine up to A-tier because I thought it was overrated. I realize now, that I was being selfish/faulty reasoning, and I should ave never attempted discredit this monster of a Pokemon. Mamoswine is just... Awesome. It can play the lead game fairly well (either as an endeavor lead or LO attacker), its practically impossible to wall (offense teams are pretty much forced to sack something if don't have Rotom-W). It's arguably the best revenge killer in the game; it's priority is extremely useful for taking down Dragon-types, Landorus-I (arguably the most dangerous sweeper in the GAME) Tornadus and Thundurus-T. Its one of the better offensive SR users, and it has a handy immunity to electricity (making it useful consistent check to Thundurus imo). When it got Thick Fat, it basically nullified the shittyness of its ice-typing. It's probably the only Pokemon in the game that benefits from its Ice subtyping due to its unique circumstance. Overall, Mamoswine is just a very good Pokemon in OU, I was stupid to not move it to A-rank before.
Volcarona: There's a lot that can be said about Volcarona, but I think we can all agree that its the best sun sweeper in the game(MAYBE 2nd to Venusaur). Its SR weakness has been sited as a massive flaw, but if you're seriously willing to make Volcarona work, your team should be dedicated to controlling SR (either via Magic Bounce, Rapid Spinning, whatever). I think it's one of the most unnoticed winners of the BW2 move tutors, because Giga Drain lets its absolutely shit on Keldeo and Terrakion at +1. Keep in mind, these are 2 Pokemon are often considered some of the best Volcarona checks in the game and they can't even it stop it at +1. It's really only stopped by Blissey (which nobody uses) and Heatran (any sun team worth their salt should use Dugtrio to KO Heatran). Volcarona is an A-rank Pokemon for sure.
Kyurem: Kyurem gets neglected for being a crappier Kyurem-B, but that couldn't farther from the truth. It still has the traits that made it a sleeper threat in the first place; Awesome bulk (with the newly added roost), dual effectiveness against Rain Offense and Sun Offense, and the ability absolutely murders stall teams. SubRoost sets are a bitch to deal with in general and Kyurem has amazing coverage (The addition of Earth Power to its movepool really does make a difference).
BKC's team, which is one of the best
stall semi-stall teams ever created, you'll notice that Kyurem absolutely devours that team. (I'd argue that it also beats down gr8's team too but whatever). Even with the existence of Kyurem-B, Kyurem is still a damn good pokemon.
Alakazam: Magic Guard is without a doubt, one of the best abilities in the game. Give one of the fastest Pokemon, (with awesome coverage) immunity to passive damage of any kind, and basically 2 lives (with Focus Sash) and turns into a badass killing machine. It's as simple as that! Alakazam is basically an amazing offensive threat, revenge killer, and stallbreaker (CM Alakazam is very effective against stall) all rolled into one. Best of all, it can body Tyranitar.
Tentacruel: Tentacruel is fodder for Sand and Sun teams... but on the other hand, Tentacruel is fucking cheap in the rain. Rain Dish basically makes it invincible, and it's capable of stalling out a ton of threats on its own. It does this in addition to being arguably the best spinner in the OU tier, so I don't see harm in moving this thing to A-tier.