How To Play As Crunch
When you get to the junkyard, you'll have to defeat crunch and n. Brio. You have to jack crunch in order to play as him. But that's the only level you get to play as him.
How To Beat Cortex [last Level]
When you have to beat cortex, they give you the mutant that slows down time. Jack it, then slow down time, then keep punching him. If he"s still spinning, wait until your power fills up, then slow down time again. And keep punching him. Then, you'll have to jack him. Just do what you wanna do to kill him.