Debug Mode:
Head to the options screen and hold down L2 and press Circle.

Play as Kohryu:
Play through arcade mode without using any continues 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.

No blocking mode:
Obtain first place in arcade mode to unlock no blocking mode.

Expert mode:
Successfully complete arcade mode without continuing to unlock a hard difficulty setting.

One-hit knockdown mode:
Obtain first place in sudden death mode to unlock one-hit knockdown mode.

High speed mode:
Win 100 fights in survival mode with one character to unlock high speed mode.

Low speed mode:
Obtain a ranking in arcade mode with all characters to unlock low speed mode.

One fall mode:
Win 20 rounds in survival mode with one character to unlock one fall mode. In this mode, the first character to fall will loose, but they will be invincible to all other attacks.

Gallery pictures:
Successfully complete the game with a character to unlock their images in the picture gallery.

Sumo Game:
To play the "Sumo Game" just get a hi-score in "Survival Mode."