Successfully complete the Pit Fighter story mode.

Successfully complete Kung-Fu story mode.

Successfully complete BJJ story mode.

Successfully complete Sumo story mode.

Win championship mode with any fighter to unlock his legend mode.

Win champion mode, tournament mode, legend mode, and progress through arcade mode to unlock an additional move for that fighter.

Big John McCarthy - View the "You Lose" screen 50 times
Bas Rutten - Win HW title a second time
Dan Severn - Win Championship Road LHW title with Frank Shamrock
Frank Shamrock - Win LHW Title
Guy Mezger - Win LHW title a second time
Jens Pulver - Win Championship Road LW title
Jeremy Horn - Win LHW title a third time
Mark Coleman - Win HW title a third time
Maurice Smith - Win HW title
Murilo Bustamante - Win Championship Road MW title.
Pete Williams - Win HW title a fifth time
Tsyoshi Kohsaka - Win HW title a fourth time

You must time these actions perfectly for this to work.Choose Arcade mode at the main screen and proceed to highlight any unlocked character you have.Then hold L2 and press R2 once every 2 seconds for 10 seconds (5 times).Let go of L2 and tap "up" direction pad 2 times then wait 5 seconds and tao "down" direction pad 2 times.Now exit back to main menu,then simply go back to Arcade mode and you will have all the characters in the game unlocked.