User blog comment:DerpyDoodle/Mewtwo's Moveset/@comment-25129545-20141029043815/@comment-25161957-20141029095043

I think that they may have already "finished" Mewtwo and are currently playtesting him.

I think there will be a lot of DLC content and all of it can be obtained all at once along with Mewtwo.

Also, he wasn't that good in Melee. I don't think they will completely copy-paste him into Smash Bros Wii U/3DS as one of their focuses is "balance".