I'm not sure how popular of an opinion this is, but to me magnet pull is pretty difficult to pull off. More often than not, the mon you're running magnet pull on can't do a whole lot versus defensive mons that can eat its physical/special attacks. However, if you can come up with other cool magpull ideas to hit opponents with the surprise factor, it makes trapping their steel types a whole lot easier.
thanks for your opinion I'm going to do some teambuildingI don't think Magnet Pull is that good this gen. Along with what Thinkerino already said there are some other issues. The only 2 steel types are Ferrothorn and Corviknight and Ferrothorn almost always runs FF. Additionally, Corviknight also often likes to run FF or VA so it's almost impossible to find a puller that can reliably oneshot both of them. You also really dont want to be running choice items, as if your intention is to trap Corviknight hitting it with the wrong SE move (Fire if its FF, Elec if its VA) means they get huge uturn momentum into whatever they want with you being locked. You can't even really run setup based magnet pullers (as in, run sth that traps a steel type and abuses it to set up to max and then tries to sweep) to reliably remove steel types since Corviknight can just uturn out.
Id say your best bet for a universally useful magpuller is rotom H since it can hit any corviknight super effectively and it has trick (which makes choice items not a liability) to cripple ferrothorn. Scarf to also trap drill, Specs to hit harder.