The hilariously overpowered legendary pokemon Mewtwo is returning to the series after a long, and justifiable, absence. His emergence comes in the form of a downloadable character for Pokemon Black and White, as well as a card for the collectible card game. Other Mewtwo-themed offerings abound. Also, check out the Mewtwo timeline to see why this classic Pokemon character was sent riding off into the sunset in the first place. Gamesradar has the story.
It comes down to a design flaw in the early Pokemon games. The Special stat worked for both attacks and defense, you see, but only a few weird attacks triggered off Special. Thus the name. Mewtwo was all Special attacks, all the time, and his Special could reach the kind of levels that can only be described with insane laughter. Once Pokemon grew a tournament scene, this became a problem.
So they booted the guy.