Hitmonlee

Hitmonlee is one of the few Pokemon in the game--let alone UU--with the ability Unburden. With its ability, Hitmonlee can double its Speed immediately and become an extremely threatening sweeper, like Yanmega and Sharpedo. That's not all Hitmonlee has going for it: it has a whopping base 120 Attack, a decent base 87 Speed, and great offensive options to utilize them with. Hitmonlee has a surprisingly high Special Defense to boot, which allows it to survive extremely powerful special attacks, such as Zapdos's Thunderbolt and Raikou's Extrasensory, and retaliate with a powerful attack of its own. Unfortunately, the fun ends there; Hitmonlee has an extremely low base Defense of 53, which makes it difficult for it to survive even resisted physical hits. However, with sufficient team support and good play, Hitmonlee can sweep whole teams.