I'm doing basic google searches but really most info seems to come from a hardly credible source. And its basically says what I posted.
Everything else comes up with rumors or is just completely dry.
Here is one of the sources that talks about Sakurai planning not to add more characters in the roster: http://mynintendonews.com/2012/07/02/smash-bros-wii-u-probably-wont-feature-more-characters/
It's difficult to determine what he means, as many fans are making their own speculations on what he meant about adding less characters. Some say the roster will still be 35/37 with some being rumored and replaced by news, while others say it will be less new characters but still have the same 35/37 in the roster. Whichever speculation is true, then I hope neither of them affects the two "new Pokemon reps per title" pattern I've theorized.