how would he know who to go for? and both magneto and exodus can fly, and the chances of magneto not putting up a magnetic sheild around his team right away, are slim to non.
flash is a non factor in this, supes is the only problem, and he would have his hands full.
so after his hand is broken after his test punch on colossus, it gets shocked by magnetos feild wich he ALWAYS has up nowadays, then gets frozen by iceman (like a kid licking a poll in the winter)
Mags goes into the fight with a forcefield up around him and Xavier, maybe the entire team, Xavier takes the majority out (or maybe him and MM just go at it telepathically) and Mags can take out most of the JLA himself. Juggs is magical, so if he punches Superman he's screwed....and your right, the Flash makes this hard, but I'll still side with team Marvel.