Mewtwo is a downloadable character in Super Smash Bros. for Nintendo 3DS and Wii U.
Mewtwo is based off of its artwork in Super Smash Bros. 4, with a clear plastic stand between its legs to help keep it up.
Created from modified Mew DNA, Mewtwo was designed to be the ultimate Pokémon™. It didn't take on any of Mew's kinder traits and only uses its intelligence to destroy its enemies. Or...so it seems. Perhaps it just feels frightened or even tormented, and that's why it lashes out. Whatever the reason, Mewtwo is not to be messed with.