 
Play the game under any difficulty setting without losing a round (not a continue). During the fight with the last Digimon before Reapermon, BlackWarGreymon will challenge you. Defeat him and Reapermon without losing a round to unlock him. 
NOTE: This only works on these Digimon: 
gumon- arGreymon- Gabumon- MetalGarurumon- Patamon- Seraphimon- 
Wormmon-Stingmon-Gatomon-Magnadramon-Omnimon.
On the Select Digimon screen, hilight one of the above Digimon and hold R1, L1, & O then press X. The Tamer will be different. | 
Submitted by WilKramerEnter KIMJOY as a password.
To receive anyone's digivolved form, successfully complete the game with them. 
To receive anyone's Mega form, successfully complete the single player game with that person. You cannot be a Mega in single player mode.
Enter LINMON as a password.
- Imperialdramon (Paladin mode)
Complete the single player with Veemon and Wormmon. (This may be harder then you thought)If you do so you'll get Imperialdramon Paladin mode.
Note: He can do the same triangle and circle technique of Imperialdramon. | 
Submitted by RyanSuccessfully complete the game with all three season three characters. 
Enter MINNYN as a password.
Enter SERIUS as a password. Alternately, successfully complete the game with Gabumon and Agumon. 
To play as the same digimon as your opponent, hilight your opponent's digimon, hold SELECT & O, then press X. Player 2 will be a different color. | 
Submitted by WilKramerSuccessfully complete the game once.
Enter KENSAN as a password. Alternately, successfully complete the game with Renamon.
Go to password at the main menu, and put in ROYBOY to get a mega digimon--WarGreymon or BlackWarGreymon! | 
Submitted by ShadowFoxEnter QRIOUS as a password.
- More Cheats, Achievements