Skarmory

Skarmory, one of the best physical walls since GSC, returns in BW to protect its team from Ubers' physical titans: Extreme Killer Arceus, Groudon, Rayquaza, and Excadrill. In fact, the steel bird is the best Swords Dance Arceus counter in general, specifically Extreme Killer Arceus, that exists. With base 140 Defense, reliable recovery in Roost, great defensive typing, and a wide arsenal of support moves such as Spikes, Stealth Rock, Whirlwind, Toxic, and Taunt, Skarmory makes for a great Pokemon to support your team. Skarmory's Sturdy ability allows it to tank and scout hits when at full health, which can prove helpful in some situations such as when facing Choice Scarf Kyogre or Palkia. Skarmory does have its downfalls, though; it is worn down quickly by common special attacks such as Surf and Focus Blast. Weaknesses to Fire- and Electric-type moves also make it prone to Fire Blast and Thunder, two moves that are very common in Ubers. Nevertheless, the armored bird's qualities are by far greater than its frailties, making it a great addition to any team, be it offensive or defensive one.