Magneto although could do some degree of harm Hulk, is simply unable to do any real damage to Hulk, and would only succeed in pissing him off. Hulk has taken and survived deadlier cosmic attacks from far more powerful entities than Magneto.
I also don't see Magneto allowing Hulk to get in any potentially deadly range, and he has a high degree of mobility due to his levitation mastery, as well as can generate strong forcefields.
It would require certain "conditions" for this fight to favor either combatant.
STALEMATE.
Originally posted by Soljer
Magneto rips him to shreds, drops him a wormhole, and BFR's him. Problem solved.
Thats cute, but not the way Magneto is portrayed in comics.
Magneto usually requires a high degree of focus and concenctration to "zone in" on micro-levels of metals such as in the blood stream to effect them at all...and to attempt this while fighting and trying to elude a hold off the Hulk would be suicide.
He also requries a degree of his focus to maintain forcefields. What Im saying is that his more powerful feats requires total concentration on one feat at a time, (eg,not multi-tasking - flying/forcefield/attacking.)