Sorry about half of the sprites being animated and half being static, I couldn't find any animated B/W Icons x-x.
Set-Up Sweeper:
Dragonite
With the advent of multiscale, Dragonite's ability to set up this generation is completely unparalleled. While CM Reuniclus is an amazing sweeper and a very potent threats to Stall Teams, it often finds its sweep stopped short by Jirachi or a clean OHKO at the hands of Choice Band Tyranitar; this is the principal difference between the sweeping abilities of Dragonite and Reuniclus. Dragonite's sweeps are so potent because they can't be ended by an attack that OHKO's Dragonite, as only a handful of moves in the metagame can actually OHKO Dragonite when Multiscale is active. There's also the fact that, Dragonite also has the ability to run many viable moves on Dragon Dance sets, so while you could be expecting the standard set, and send in your Heatran to beat it, Earthquake comes out of nowhere and takes it out, Hurricane does the same to Tangrowth, and SubDD troubles even the most consistent 'counters' to Dragonite's only carrying a Dragon Attack and possibly a fire attack to go along with it. Dragonite's absolute dominance over many walls in the OU Metagame always leads me to consider Tangrowth as my first option when choosing a Physical Wall, when I'm teambuilding, as Tangrowth is one of the few Pokemon that can stand up to the standard set; it walls a ton of other stuff, but that's a huge sell. Dragonite's sheer versatility and the fact that it can set up so easily with Multiscale and its amazing bulk absolutely solidify it as the best setup sweeper of BW OU, in my mind.
Non Set-Up Attacker:
Terrakion
Had to give this to my boy Terrakion, or rather, his Choice Band set. Choice Band Terrakion is by far one of the most powerful Pokemon in the tier, and his astonishing strength is backed by a respectable 346 Speed with Max EVs/Jolly, allowing it to outspeed a good amount of the tier while beating them down via its powerful STAB Attacks. Speaking of STAB Attacks, Terrakion's CB Close Combat is absolutely insane and even 2HKOs Pokemon that resist it, like Zapdos [Offensive], without any need for Stealth Rock on the field, while Stone Edge provides even more potent STAB to round out Terrakion's coverage nicely in conjunction with X-Scissor and Earthquake/Quick Attack. In addition to all of this, Justified is a very underrated ability, if Terrakion comes in on a Crunch or another Dark attack, then there are only a handful of Pokemon that can expect to survive the impending attack afterwards, Terrakion is that powerful. Terrakion is also one of the better Scarfers in the metagame, hitting a higher speed than even Garchomp, while maintaining a beneficial Attack stat of 357 with a full EV Investment. Again, Justified helps the Scarf set a lot as well, as you basically have a Choice Band Terrakion after the Scarf Set gets hit with a Dark Type move, except it has a Speed Stat of 519 [again, assuming 252/Jolly].
Wall:
Tangrowth
I already gave Tangrowth a mention in the bit about Dragonite, but I feel that I should expand on why he's arguably the best physical wall in OU. I do realize that the title is "wall", so I'll just give the title of best "Special Wall" to Blissey and continue on about Tangrowth. Anyhow, Tangrowth received the amazing ability Regenerator via Dream World, allowing it to get multiple chances to take down a threat, or just get its health back in general, which in some cases, is more beneficial than a move like Recover. While Tangrowth may not have the greatest defensive typing, it boasts a Base 100 HP Stat and a Base 125 Defense stat, giving it nearly unrivaled Physical bulk, too. Tangrowth also has the ability to "hit back" and with a base 100 Attack Stat and Base 100 Special Attack, does so well. Between Power Whip/Giga Drain, Hidden Power [Ice] and Earthquake, it's going to be quite hard for a Pokemon actually set up on Tangrowth without losing a large chunk of its HP, and Leech Seed adds pressure, Sleep Powder is yet another potent tool that Tangrowth uses to halt sweeps. All in all, Tangrowth is just so amazing and reliable, I always find myself making sound plays with it and its survivability is amazing. If you already haven't, take Tangrowth for a test drive.
Annoyer:
Rotom-W
No Pokemon rivals Rotom-W in its ability to be annoying. Rotom's amazing defensive typing and powerful dual STAB make it a force to be reckoned with on both the offensive and defensive side of the spectrum. In addition to this, Rotom-W rips through Stall and Offensive teams alike by forming what is one of the greatest tandems in the metagame with Scizor and spamming Volt Switch like there's no tomorrow, while Scizor takes care of what Rotom doesn't. If it didn't get any worse, Rotom also carries Will O Wisp, which cripples Pokemon that would otherwise tank its attacks and then beat it, like Specially Defensive Choice Band Tyranitar and building up residual on Pokemon like Gastrodon all the same. Finally, Rotom can totally turn the tides on a situation with Pain Split, annoying the likes of many Pokemon that were previously at full health, especially Blissey, which loses a nice 50% of its health to Rotom and ends up having to waste some of Softboiled's PP.
Spinner:
Starmie
I think Starmie retains its spot as the premier spinner this generation, it's offensive capabilities as a spinner are unparalleled now that Excadrill is gone, and it beats the majority of Spinblockers out there. Starmie is also in an excellent speed tier and gets good coverage with Hydro Pump and Thunderbolt/Ice Beam, although the former is usually better on a dedicated spinner due to the fact that it beats Jellicent. In addition to this, Starmie gets access to Recover, while it's not bulky by any means, this certainly comes in useful, as many other Spinners can't heal off the damage they take from incoming Entry Hazards.
Phazer:
Skarmory
I'd say that Skarmory deserves the title of "Best Phazer" in OU, although it isn't able to stop Baton Pass teams like Dragon Tail Dragonite, it's Phazing is just so effective, that it wouldn't be wise not to call it the Best Phazer. With its amazing Physical Defense and access to the revamped Sturdy, it's able to get a sometimes crucial Whirlwind off on so many threats, something not every Pokemon can do. Not only that, but Skarmory's Whirlwind just becomes so much more threatening with the Spikes that it lays. Phazing a threat is beneficial in itself, but Phazing a threat and having that same Pokemon take 25% residual? Yes please. Skarmory is just such a potent user of Whirlwind and almost always seems able to use it, it's ability to Phaze so well is certainly one of the selling points it has over other Physical Walls. While it may be hard to call a Pokemon the "Best Phazer", due to the nature of Phazing moves, Skarmory's ability to Whirlwind with ease, in tandem with the Spikes it bombards the opponent with, solidify it as the "Most Effective" Phazer in the OU Metagame.
Underrated Threat:
Durant
As much as Sharpedo is deserving of this, I think it's time the Hustla' spends some time in the spotlight. Durant is so powerful it's incredible, it has an adorable 109 Base Speed, allowing it to outspeed a good portion of the tier, as well as nearly edge past the Muskateers and Infernape. With a Jolly Nature and a 252 EV Investment, Durant hits an attack stat of 475, thanks to Hustle. While most of its attacks [Stone Edge in particular] have a good chance of missing initially, Durant kicks it into hyperdrive after a Hone Claws boost, retaining its lost Accuracy and boosting its Attack Stat up to 712. Durant also has the Defense to shrug off a Physical Hit and can disregard Status that would otherwise hinder it by holding a Lum Berry. I've always found Durant to be an underrated sweeper with amazing potential, and while it may be "gimmicky", it's one of the few offensive Pokemon I love to play with, due to it's sheer power and Speed Tier to pull off a feasible sweep.
