Well, there's no such thing as magnetic energy, there's electromagnetic energy, and that's what Mags controls. Vulcan has shown manipulation of heat, light, force, and possibly electric energy, but never electromagnetic. Considering his Omega status though, and his shows of power, it's possible. However, Mags still puts Vulcan over his knee.
dunno about Mags putting Vulcan over his knee. He was even shown manipulating Adam Warlock's "quantum magic". Can't remember where, but it might have been in a GotG WoK crossover. I'm guessing he shouldn't have a problem messing with Mag's magnetic abilities.
The thing is Vulcan is more hype than anything else, his energy manipulationn powers are not limitless even if his development potential with them is supposed to be.
He has been defeated by a sundipped havok, black bolt and polaris, all of which are energy manipulators and blasters. Another problem here is that magneto doesn't just control electromagnetic radiation, which is energy, but the electromagnetic force created by the existence of matter itself, which is not exactly energy. BB too controls electrons and their behavior.
I think either of the two veterans can take the emo *****.