At one point between rounds on the Wii game, instead of his usual advice, Doc tells Mac to remind him to pick up some milk after the fight. It just comes outta nowhere, making it hard not to at least chuckle at it.
"Join the Nintendo Fun— I mean, Club Nintendo today, Mac!"
"The original Nintendo Fun Club line was pretty funny and out of nowhere as well."
Decking Narcis Prince in the face can be quite amusing.
Don Flamenco's ridiculously over-the-top defeat animation in the Wii version. He holds up a rose similar to old cartoon characters when they pretended to "die."
Mr. Sandman's Title Defense victory cutscene, which has the referee trying to raise his arm in victory, but can't even budge it, and Sandman then lifts his arm into the air with the referee still holding onto it.