Hokuto no Ken: Seiki Suesuku Seishi Densetsu Codes -

Fight against CPU:
Select versus mode, then press Select on the controller that you wish to have the CPU control.

Alternate costumes:
Highlight a fighter, then press R1 at the character selection screen in versus mode.

Fight as Bosses:
Defeat a Boss without using a continue in story mode to unlock that character in versus mode.

Secret mode:
Successfully complete story mode without using any continues to unlock a hidden mode that lets you defeat as many enemies as possible in 30 second rounds.

Skip ending sequence:
Press Start during the ending FMV sequences.