Actually, a better example is Guilty Gear. Along with an array of universal defensive mechanics, the roster is incredibly diverse and balanced. Sure, the knockdown game is one of the largest parts of the game, but it doesn't affect the diversity that much from what I've seen.
I love both games, and it think that as far as balance goes there is something to consider in games like these. S3 came out in 3 different versions, and Guilty Gear has come out in millions of versions. I just point this out because despite the fact that these games both cater to a competitive audience they still didnt get it right the first time. Both were modified for balance in each version, eventually culminating in the finished products they are now. I am personally a little bumed that Sakurai has he does not foresee downloadable content as being part of SSB4, because thats one of the ways that they might achieve the balance thats nearly impossible to get by just balancing during development.