In arcade mode, select your character with charge moves. When the fight begins, exit the game by pressing SELECT + START. Go to arcade mode again and pick the same character you played the first time. Now all the character's charge moves can be done without charging the 2 seconds. The only drawback is you cannot perform supers.
Special Moves
If you are having trouble pulling off your favorite character's special moves on the small GBA controls, this code can help you out a bit. During a 1p game, tap Up Up Down Down Left Right Left Right B then A without pausing the game. You need to do it very quickly. Once the code has been entered you will be able to pull off special moves by simply tapping a direction on the D-pad and the correct button.
Unlock Akuma
Earn 5000 points to unlock Akuma.
Unlock Shin Akuma
Earn 9999 points to unlock Akuma.
Unlock Survival Mode and Time Attack
Two additional modes will appear on the main menu once you have beaten the game a couple times. The first mode is a Survival mode, and the second is a Time Attack.