Flashback (Classic Iceman, WWII Captain America, Original Daredevil, Classic Iron Man, Original Ms. Marvel, Classic Wolverine, Original Ghost Rider): +15% Max Health
Martial Artists (Black Panther, Captain America, Daredevil, Nick Fury): +15 Striking
Marvel Knights (Spider-Man, Dr. Strange, Daredevil, Black Panther, Luke Cage): +6 to all stats
Marvel Royalty (Black Panther, Dr. Strange, Thor, Storm): +60% Credit Drop
Natural Forces (Human Torch, Iceman, Storm, Thor): 5% Damage inflicted as health gain.
Natural Leaders (Captain America, Dr. Strange, Mr. Fantastic, Nick Fury, Storm): +5% XP
New Avengers (Captain America, Spider-Man, Iron Man, Luke Cage, Spider-Woman, Wolverine): +5% to All resistances
New Fantastic Four (Wolverine, Luke Cage, Ghost Rider, and Spider-Man): +15% maximum energy
Power Platoon (Ms. Marvel, Silver Surfer, Thor, Iron Man): +20 energy per KO.
Raven Ultimates (Silver Surfer, Thing, Colossus, Iceman, Deadpool, Moon Knight): +6 to all stats
Secret Defenders (Silver Surfer, Hulk, Ghost Rider and Dr. Strange): +5% damage
Scorchers (Ghost Rider, Human Torch, Storm, Thor): +10% reduced power cost
Supernatural (Blade, Dr. Strange, Thor, Ghost Rider): +5 Health regeneration
Think Tanks (Spider-Man, Mr. Fantastic, Iron Man, Dr. Strange): 15% maximum health
X-Men (Storm, Iceman, Colossus, Logan): +15% maximum energy

Black Panther
Collect the five Black Panther action figures. One is found in each Act.

Win the toy grab mini-game in the Carnival at Murderworld.

Dr. Strange
Save Dr. Strange in Mandarin’s Palace.

Ghost Rider
Trade places with Ghost Rider in Hell in order to save his soul

Nick Fury
Successfully complete the game.

Hard mode
Successfully complete the game under the normal difficulty setting.

Second and third alternate costumes
Gain between two and four levels with a character. Alternately, defeat 30 enemies with a character to unlock his or her second costume. Defeat 175 enemies with a character to unlock his or her second costume.

Fourth alternate costume
Complete the Combat Training challenge for a character. Alternately, get a “Bronze” rank in a character’s Comic Mission to unlock his or her fourth costume.