Check your e-mail, Smash Bros . players. You might find a surprise. If you managed to register both the Wii U and 3DS versions of Super Smash Bros., then you should be receiving download codes for Mewtwo for both versions soon. Note that each code will have to be entered individually into the Nintendo Wii U or 3DS eShop.
Mewtwo is an interesting character. He retains most of his moves from Melee , but the system changes in Smash Bros. for the 3DS and Wii U make him play remarkably differently. He is still a very evasive character, though, and he has many disjointed hitboxes and powerful throws. We will see how he stands up to the rest of the cast.
Source: Nintendo