During gameplay collect the little Justice League of America shields to exchange for the corresponding hero/costume.

Heroes

Aquaman - 26 Shields

Huntress - 53 Shields

Green Lantern-Kyle Rayner - 55 Shields

Hawkgirl - 70 Shields

Green Arrow - 76 Shields

Green Lantern-Hal Jordan - 84 Shields


Alternate Costumes

Martian Manhunter True Form - 15 Shields

Flash Jay Garrick - 21 Shields

Green Lantern Retro - 23 Shields

Zatanna (Classic Blue) Suit - 25 Shields

Martian Manhunter (Modren) Suit - 29 Shields

Green Lantern (Bold) Suit - 30 Shields

Superman Black Recovery Suit - 32 Shields

Zatanna (Identity Crisis) Suit - 38 Shields

Wonder Woman (Toga) Suit - 44 Shields

Flash (Walter West) Suit - 48 Shields

Batman Clasic Blue - 59 Shields

Wonder Woman Biker Style - 61 Shields

Superman Earth 2 - 65 Shields

Batman Infiltration Suit - 74 Shields

Superman Kandor - 91 Shields

Enter the following codes to unlock the corresponding effect in the game.

Unlocks Everything:
Press Down, Left, Up, Right.

Unlock 20 Free Shields:
Press Up, Up, Down, Down.

Unlock 25 Boosts:
Press Left, Right, Left, Right.

Max Abilities:
Press Right, Down, Right, Down.

Invincibility:
Press Left, Down, Right, Up, Left, Down, Right, Up.

Unlimited Energy:
Press Down, Down, Right, Right, Up, Up, Left, Left.

Unlock Challenge Missions:
Complete the game on Medium difficulty setting to unlock Challenge missions where you can select any character.