YuYu Hakusho: Spirit Detective

Defeat Ghosts Hint
Hold the A and B buttons, while pressing Left and Right on your control pad until they come off.
(Thanks to GotenksUL@aol.com)

Unlock Arcade Mode
Beat Tournament Mode.
(Thanks to rein-gaiden@hotmail.com)

Unlock Tournament Mode
Beat the game.
(Thanks to rein_gaiden@hotmail.com)