Zander

The kartana excuse really only works this Gen., while magnezone's been running high-Speed Choice sets from it's introduction. My guess is that it's due to the fact that magnezone has no means of active recovery, and is thusly prone to being worn down throughout the fight simply by switching in to do its actual job (hunting down, entrapping, and ultimately elimination opposing Steel Types). It doesn't want to take any more blows than it already has to, and the best way to make sure that doesn't happen is to blast your target to smithereens before they can even move!

I'm personally a little annoyed that Smogon only has Magnet Pull sets for it (and probopass), but that may have something to do that I play in-game rather than comp.- the need to off Steels isn't quite so significant in the majority of fights, no?

magnezone is limited by its stats, other than special attack and to a lesser extent defense, being rather bad. id argue magnet pull is the only reason its still in ou, even. sturdy had a fall from grace with stealth rock appearing on pretty much every team.

ingame trapping isnt even as important, as ai trainers often dont even switch out to begin with. so ingame id 100% go with sturdy magnezone.

Analytic Magnezone is cool too.