Knockout Kings 2000 (N64)Big Gloves:
Pause the game and press C-Up, C-Down, C-Up, C-Up, C-Down. Repeat to de-activate.
Big head mode:
Pause the game and press C-Left, C-Right, C-Left, C-Left, C-Right. Repeat to de-activate.
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.
Move away from your opponent, hold Z and sweep the Analog-stick in circles. Also try tapping Z repeatedly without moving the Analog-stick.