Nintendo said there will be 13 fighters going up against Little Mac and his trainer Doc Louis. Nine of those 13 include Glass Joe, Don Flamenco, King Hippo, and Von Kaiser. So that’s a total of four that we know will be in the game but the other 9 fighters have yet to be announced be Nintendo.
Souce:
http://kotaku.com/5177601/new-wii-punch+out-details-sneak-out-from-nintendo