Zatch Bell cheats and cheat codes for Gamecube

Unlock Maestro as palyable character:
You must beat Time Attack mode minimum 300 times. Then, Maestro will 
challenge you. Beat him.

Unlock Zeon/Deufo
Finish Zeon's Story Mode. 

Unlock Characters:
Bari - Finish single player mode as Kanchome. 
Earth - Finish single player mode as Ted. 
Keith - Finish single player mode as Bari. 
Rein - Finish single player mode as Gash. 
Ted - Finish single player mode as Umagon. 
Victorim - Finish single player mode as Reira. 
Zeon - Finish single player mode as Tio. 
Zofis - Finish single player mode as Brago. 

Unlock Milordo-Z
Purchase all Spell cards in Bonus mode

Unlock Mohawk Ace
Purchase all Mamodo cards in Bonus mode

Unlock Dr. Riddles
Beat Dr. Riddles in any Story mode

Unlock Laila and Albert. 
Purchase  all Event cards in Bonus mode.

Unlock Zeno and Dufort
Hit Up, Up, Down, Down, Left, Right, Left, Right, X, A at the title screen.

Unlock Zeno and Dufort in Story mode
Hit Up, Up, Down, Down, Right, Left, Right, A, X at the title screen.

Unlock Password option in the Bonus menu:
Beat the first 10 opponents in Zatch Bell's story
Enter cheat code: "UCKAHEIT" to unlock Laila and Albert. 

theczball allows you to get 10 randam cards!