[Illusion]

Originally Posted by Alpha

Yep. I'm hoping it'll still be possible to get him without getting both versions of the game since I don't have nor am I planning on getting a Wii U.

On how they worded it they said that "Mewtwo's free with the purchase and registration of both Super Smash Bros games" Free as in he would be originally be up for purchase if not for the reason before it. Hence, Mewtwo will be paid DLC content unless you have registered both games.