Magneto is the MASTER of Magnetism, not some ****ing pansy *****. Hulk is NOT the type of character who gives Magneto problems. Cable, Prof. X, Phoenix, these are characters that really **** with Magneto, Hulk is not one of them. Magneto is NOT stupid, he is genius level, most notably in biology, genetics.
1. Magneto can do anything he wants to Hulk. Hulk can run at him, and Magneto rips the ground right out from under him. Hulk can jump at him, and Magneto pushes him away with a magnetic force field.
2. Magneto is not concerened with Hulk, or anyone who looks/acts like him. Hulk is underneath him. This is why I say that Magneto wouldn't even bother fighting him. That, and that if he did, Hulk would eventually tire him out, -he knows this-. Why waste time and energy on something you are unconcerned with, and have a simple solution to? Magneto doesn't need a super strong sphere to hold Hulk forever, he would just want him out of his hair. Collapsing a few cars, and encasing Hulk in the resulting sphere, and then propelling him -wherever he wants- including space, counts as a victory.
Hulk has pure strength, NOT power. There's a subtle difference, and that difference prevents Hulk from having a shot at winning.