Complete the following tasks to unlock the corresponding costume

Unlock 2nd Costume:
Defeat 30 enemies Controlling that Character

Unlock 3rd Costume:
Defeat 175 enemies Controlling that Character

Unlock 4th Costume:
Get Bronze in that Characters Comic Mission

Unlockable Heros and Modes
Complete the following tasks to unlock the corresponding effects. There are seven playable characters that can be unlocked.

Unlock Hard Mode:
On Easy or Normal mode complete the game

Unlock Nick Fury:
On Easy or Normal mode complete the game

Unlock Silver Surfer:
Defeat Galactus

Unlock Dr. Strange:
In Act 1 rescue him from Mandrin

Unlock Ghostrider:
In Act 2 rescue him from Mephisto

Unlock Black Panther:
Collect Black Panther Action Figures throughout the game

Unlock Daredevil:
Collect Daredevil Action Figures throughout the game