If you complete the following tasks you will be able to get an assist from the corresponding character.
After beating Tinkerer keep selecting the 'bad' choice when asked by computer.
Select to save Black Cat when you fight her (pick the 1st choice when asked by Smythe)
Before fighting Kraven keep selecting the 'bad' choice (the 2nd/3rd choice).
Before you fight with Jessica Drew Select to help S.H.I.E.L.D crew from the symbiote.
Select the 'bad' choice (2nd choice) when you asked by a man who says he can divert the train containing symbiote.
Choose to free Shocker when you have defeated him.
When you have defeated Shocker take him to jail.
When you have defeated Tinkerer keep selecting the 'good' answer when asked by computer.
When you beat any level or buy the ultra rare power ups you will be able to get a random assist from the following characters - Mysterio, Night Crawler, Wolverine, Galactus, Hypno Hustler Ctylok.
Added by: Sanzano Dec 20th 2008, ID#2239