Mewtwo

Mewtwo, also known as the classic "God" of Pokemon, is certainly no slouch. Its offensive stats and huge Speed coupled with its amazing offensive movepool, giving coverage on pretty much any Pokemon, are hard to compare with other Pokemon. Mewtwo might have to share its throne with Kyogre, Darkrai, and other powerful threats; however, Mewtwo has a lot going for it with its "perfectly placed" stats and vast movepool. One of Mewtwo's most fearsome qualities is its amazing versatility. It can function well as a sweeper, a wall to many threats in the Ubers metagame with its underestimated bulk and plethora of defensive moves, or a supporter, so one must be extremely careful of Mewtwo's sheer unpredictability. In fact, Mewtwo's many skills make it pretty much uncounterable. Mewtwo's only bad qualities are its bad STAB and lack of resistances that a lot of other Uber Pokemon can boast, but these are very minor faults. "Fear" is the one thing you should think about when facing a Mewtwo, as it is one of the most dangerous Pokemon in the game.