Team Bonuses:
Certain character combinations unlock special boosts.

Assasins: +60% to Shield Credits Earned:
Wolverine, Elektra, Deadpool and Blade

Classic Avengers: +5% Damage:
Capt. America, Iron Man, Thor and Ms. Marvel

Air Force: +15% Max Health:
Any four heroes who can fly (i.e. Ms Marvel, Iron Man, Spiderwoman, Thor, etc.)

Fantastic Four: +20 Health Per Knockout:
Thing, Invisible Woman, Human Torch and Mr. Fantastic

Raven Ultimates: +6 Striking, Body, and Focus:
Silver Surfer, Deadpool, Thing and Invisible Woman

Fantastic Four:
20 Health per KO Mr. Fantastic, In

Avengers : +5% damage:
Captain America, Thor, Iron Man, Spider-Woman, Ms. Marvel

New Avengers : +5% All Resistances:
Captain America, Luke Cage, Wolverine, Spider-Man, Spider-Woman

Power Platoon : 20 Energy per KO:
Silver Surfer, Iron Man, Ms. Marvel, Thor

Bruisers : +15 Striking:
Thing, Captain America, Luke Cage, Ms. Marvel

Agile Warriors : 10% Reduced Energy Cost
Spider-Man, Spider-Woman, Elektra, Deadpool

Femme Fatale : +5% Damage
Ms. Marvel, Storm, Invisible Woman, Elektra, Spider-Woman

Natural Forces : 5%Dmg inflicted as Health Gain
Thor, Strom, Human Torch, Ice Man

Unlockables:
Do the following tasks to unlock the following characters or modes.

Black Panther - Collect Black Panther Action Figures throughout various acts
Daredevil - Collect Daredevil Action Figures throughout various acts
Dr. Strange - Rescue him from Mandrin in Act 1
Ghostrider - Rescue him from Mephisto in Act 2
Hard Mode - Complete the game on easy or normal mode
Nick Fury - Complete the game on easy or normal mode
Silver Surfer - Defeat Galactus
Blade - Play Crane Game in Murder World

Unlock hidden characters:
At the shield access point, choose chance team, Choose the member you want to change, to select from the other characters. At this point enter in the code

Unlock Silver Surfer - Down, Left, Left, Up, Right, Up, Down, Left, Start
Unlock Dare Devil - Left, Left, Right, Right, Up, Down, Up, Down, Start