Unlock All Modes
On the title screen, press A, UP, A, L, R, RIGHT, L, RIGHT, A, DOWN, RIGHT. Now press L, RIGHT, A, R, UP,L, RIGHT, B, A, UP, RIGHT, DOWN, RIGHT.
Unlock All Fighters
On the title screen, press LEFT, RIGHT, DOWN, RIGHT, L, L, A, L, L, B, R, A, UP.