Fighting Illusion: K-1 Revenge

Alternate character color:
Press L1 + Circle while selecting a character.

Sound test:
Hold Start and press L1 + L2 + Select + Down at the title screen.

Fight as Animal:
Select single player mode. Then, highlight Stan The Man at the character selection screen, hold L1, and press Start.

Fight as Master Ishi:
Successfully complete the game in single player mode using one character. Note: This also unlocks James Harrison.
Information in this section was contributed by izzyherr.

Fight as Hidefumi Minatoya:
Complete more than 100 combos under the combo training mode.

Hyperspeed fighting:
Hold Circle during a CPU vs. CPU match in tournament mode.
Information in this section was contributed by izzyherr.