User blog comment:Klaus00/RANT ABOUT DR. MARIO!!!!!!/@comment-32390199-20140912150102

Imo the game only is missing Mewtwo, Ridley and Isaac. However I still have a certain feeling that there will be new characters announced during the gap of 3DS and Wii U. And that those characters can be downloaded for free on 3DS and are unlockables on the Wii U.

Nobody has spotted Isaac yet. We still don't know anything about Ridley as Pyrosphere is on the Wii U and Mewtwo still has his chances. I really have a hunch Mewtwo will return. He was such a requested character, and they brought back Dr. Mario which means if you're cut, it doesn't mean you're cut forever.