Mishra

Successfully complete Quest mode using a preset duelist and deck.

Get Tsabo Tavoc

Successfully complete Arcade Duel mode.

Get Volita

Successfully complete arcade mode as Kuldan.

Get Maraxus

Successfully complete arcade mode as Volita.

Hidden Level

At arena select screen press L + R, Left, Up, X, Up, Right, Y, L + R.

All Duelists

At character select screen press L + R, DOWN, UP, X, WHITE, UP, X, BLACK, UP, X, L + R.

Easy win against blue computers

This is a good hint for anyone who is surfing cheatingdome and has trouble with beating blue computers. Never kill Blue Turtles on purpose,one time my opponent had five out and couldn't do anything,computers aren't smart enough to know they should kill they're own creatures sometimes. Hope this works, I beat the game in 3 days so I know what I'm talking about.