Play as Leann Caldwell in versus mode
Play through the entire game, only selecting Kou. After you defeat Duragon for the final time you will view a FMV sequence where you have to fight Leann. Defeat her to unlock her in versus mode.

Play as Wong Leung in versus mode
Play through game with any character, but do not use Sion in the fight against Kaldea, and after that fight use Sion to complete the game. After you defeat Duragon for the final time you will view a FMV sequence where you have to fight Wong. Defeat him to unlock her in versus mode.

Play as Topless Duragon in versus mode
Successfully complete the game three times using any character. After defeating Duragon for the second time, he will get up again and fight topless. Defeat him to unlock that version of him in versus mode.

Bonus characters
Successfully complete story mode to unlock characters in versus mode each time that it is finished.

Hidden FMV sequence
Successfully complete story mode with Sion.

Alternate costumes
At the character selection screen, hold L1, L2, or R2 and choose a fighter. Note: This has no effect in story mode.

Increased character rank
Every time story mode is completed, the rank of the extra characters in survival and versus modes will increase. This does not include Volt, Sion, and Kou.