Easy knock
Hit your opponent until your meter is full and then hit R + L + KICK (A or B) and you will knock him down even when he has his block on.
In the training mode go to OFFENSE and hit the blue guy like this: DOWN + A (twice) DOWN + B (twice) I think it's the only way to hit him 30 times.
Big head mode
Pause the game anytime and press c-left, c-right, c-left(x2), c-right.
Big glove mode
Pause the game any time and press c-up, c-down, c-up(x2), c-down.