Unlock Assist

Big Wheel: 
     Keep choosing the bad choice when you asked by computer 
     (after beating Tinkerer)

Black Cat: 
     Choose to save Black cat when you fight her 
     (pick the 1st choice when asked by Smythe)

Hobgoblin: 
     Keep choosing the bad choice (the 2nd/3rd choice) 
     before fighting Kraven

Jessica Drew: 
     Choose to help Shield crew from the symbiote 
     (before you fight with Jessica Drew)

Luke Cage: 
     Make the bad choice (2nd choice) when you asked 
     by a man who say he can divert the train containing symbiote

Random Assist: 
     You can get mysterio, Night Crawler, Wolverine, Ctylok, Galactus, 
     Hypno Hustler randomly by beating any level or buying the ultra 
     rare powe ups

Shocker: 
     choose to free Shocker after defeating him

Solidarity: 
     Bring shocker to jail (after beating him)

Storm: 
     Keep choosing the good answer when you asked by computer 
     after defeating Tinkerer