Breaking News.
Evidence has surfaced that MF Leaker knows nothing. He's just been leaking images that have come into his possession, and people who actually have information may have tested this by giving him an image, which he went ahead and posted on the Internet.
So his credibility is heavily into question, especially when you consider the above in combination with his fake DLC leak. Therefore, his actual remaining character allusions (Mewtwo, Dixie, Impa, Ridley, Mach Rider) is likely to be false.
This doesn't mean that some or all of those characters won't be in the game; it only means that if they're in, it's not because MF Leaker said so.