I've been playing Rocky on Gamecube. Fun, but broken. Dodge a punch and then hit a guy in the ribs 40 times in a row with body jabs and throw in some body straights will usually get you a knockout. Also for some reason the farther you get in the movies, random made up generic boxers between big fights are tougher than Apollo Creed, Clubber Lang, and Drago. Tommy Gunn is the best boxer in the game.
It was only $5.00. The final fight against Tommy Gunn when you knock him out and then punch out the Don King ripoff is actually more entertaning than the entire movie of Rocky V. Maybe because its over in less than 5 minutes.