Debug Mode (Japanese Version Only):
Enter the options screen from the main menu, then hold L2 and press .

Play as Kohryu:
Play through arcade mode until you face Kohryu on stage 5. Defeat him to unlock him as a playable character.

Play as Uranus:
Play through arcade mode and defeat Xion without using any continues up to that point. Defeat Uranus to unlock her as a playable character.

Extra Mode:
Play through survival mode and defeat more than nine enemies to unlock extra mode in the options menu. Continue defeating more enemies in survival mode to unlock more survival games in extra mode.

Infinite Replays:
Press the Triangle button as the replay is going to play it again. Keep pressing it and it'll just keep playing. It's a great way to rub it in when you KO your friends.

One Fall Mode:
Win 20 rounds with a single character in survival mode to unlock thi option. In this mode, the first fighter to be knocked down (notstaggered) is KO'ed.

Sudden Death Survival Mode:
Survive 9 fights in survival mode to unlock this option. In this mode, one hit kills you or your opponent in survival mode.

Super Difficulty:
Beat Arcade mode once without continuing on default to unlock thisoption. In this mode, the CPU isset on the highest difficulty and you are in survival mode.

No Guard Mode:
Get first place in arcade mode to unlock this option. In this mode, you and your opponent can not guard (heavy or normal), with the exception of the guard moves (green electric moves) in survival and verses mode.

Low Speed Mode:
Gain a rankin with each character n arcade mode to unlock this option. In this mode, all moves except throws are at half speed but do 200% damage.

High Speed Mode:
Win 100 battles in survival mode with a single character then enter your name in the records to unlock this option. In this mode, all moves except throws are at double speed but do 40%.

One Hit Knockdowns:
Get first place in sudden death survival to unlock this option. In this mode, you and your opponent can knock eachother down in one hit and do double damage in survival and versus mode.

Hyper Beast Mode:
Win ten fights in arcade mode and record your name to unlock this option. In this mode, you and your opponent are always in hyper beast mode (including the unlimited beast drives).

Thanks to Revolution readera Robert Smitha, Mamadou Mbaye and Gavin Alford!