Instructions
Add outside cards to your game by selecting the "Password" option in the game's main menu. Enter one of the passwords from the reference page into the password screen. Select the "Done" option when you have entered the password.
Get unlimited cards for your game by using a second copy of the game and a second Game Boy Color. Add cards to the second copy of the game using the available passwords, and trade these cards to your game. Then erase the game file on the second copy of your game and restart the process.
Summon the "Blue Eyes Ultimate Dragon" in battle by placing three "Blue Eyes White Dragon" cards on the playing field and sacrificing them all. The "Ultimate" card then will be added to your deck.
Unlock the secret DarkNite character by defeating all of the duelists in ancient Egypt five times.
Keep a perfect record in the game by turning your Game Boy Color off as you are about to lose. The game will not register your loss.
Summon the "Red Eyes Black Metal Dragon" during battle by playing your "Red Eyes Black Dragon" card, then using a "MetalMorph" card on it. This will change your original card into a "Red Eyes Black Metal Dragon" card.
Win battles instantly by placing all five Exodia cards into your fight deck. Once all five Exodia cards are in your hand, Play a "Swords of Revealing Light" card to freeze your opponent, then play all five Exodia cards to win the battle.