'We aren't working on anything at the moment'

Mewtwo is coming to Super Smash Bros. next spring, but Masahiro Sakurai explained to IGN that, "releasing that character is an experiment meant to act as a foothold in content distribution; thus it's simply meant as part of the service we're providing to gamers."

Speaking to Videogamer, Sakurai said the studio is not working on any other Super Smash Bros. DLC at the moment.

"I understand that DLC could add a lot to the appeal of Smash Bros., and I appreciate that a major part of the excitement for these games come from which characters will appear in the roster, so I think fans could really enjoy DLC that could keep this excitement going. However, I think there might be criticism that we are cutting up content to sell characters one by one, or that we are adding things later that should have been there from the start.

...what I can say now about paid DLC is that we aren't working on anything at the moment. We've put all our efforts into making the actual game. Creating DLC would involve large additional costs and require the involvement of a lot of people."

Super Smash Bros' Sakurai on Reggie, patch support & the problem with leaderboards [Videogamer]