User blog comment:Four4/Possible leaked DLC/@comment-835264-20140929215026/@comment-6604133-20140929222939

I wouldn't say "zero chance". They could just change how to unlock his trophy by beating Classic with him, and get a different character to replace how he was originally unlocked. I'm not sure how it would work for people who've already unlocked Mewtwo's trophy, but keeping Mewtwo out AGAIN would just be plain stupidity on their side.