Unlockable Heroes and Outfits:
By collecting orange shields throughout the game, you can purchase new heroes or alternative costumes. Once you have obtained enough orange shields, access the menu by pressing the select button.
Batman Alt. Costume: Classic Blue 59 Shields
Batman Alt. Costume: Infiltration Suit-Batman Beyond 74 Shields
Flash Alt. Costume: Jay Garrick 21 Shields
Flash Alt. Costume: Walter West 48 Shields
Green Lantern Alt. Costume: Retro 23 Shields
Green Lantern: Alt. Costume: Bold 30 Shields
Martian Manhunter Alt. Costume: Modren Look 29 Shields
Martian Manhunter Alt. Costume: True Form 15 Shields
New Hero: Aquaman 27 Shields
New Hero: Green Arrow 76 Shields
New Hero: Green Lantern-Hal Jordan 84 Shields
New Hero: Green Lantern-Kyle Rayner 55 Shields
New Hero: Hawkgirl 70 Shields
New Hero: Huntress 53 Shields
Superman Alt. Costume: Black Recovery Suit 32 Shields
Superman Alt. Costume: Earth 2 65 Shields
Superman Alt. Costume: Kandor 91 Shields
Wonder Woman Alt. Costume: Biker Style 61 Shields
Wonder Woman Alt. Costume: Toga 44 Shields
Zatanna Alt. Costume: Classic Blue 25 Shields
Zatanna Alt. Costume: Identity Crisis 38 Shields

Cheat Codes (Xbox):
Pause the game, and enter these codes with the D-pad while holding both the L and R triggers.
Code Effect
Up, Up, Down, Down Get 20 Shields
Left, Right, Left, Right Gives 25 Random Boosts
Down, Down, Right, Right, Up, Up, Left, Left Infinite Energy
Left, Down, Right, Up, Left, Down, Right, Up Invincibility
Right, Down, Right, Down Maxes Out Abbilities
Down, Left, Up, Right Unlock all Costumes

Cheat Codes (PS2):
At the pause menu, hold down all 4 L and R buttons.
Code Effect
Up, Up, Down, Down Gives 20 shields
Left, Right, Left, Righ Gives 25 Random Boosts
Left, Down, Right, Up, Left, Down, Right, Up Invincibility
Right, Down, Right, Down Maxes out abilities
Downx2, Rightx2, Upx2, Leftx2 Unlimited Energy
Down, Left, Up, Right Unlock everything