I said anti-tank but I meant anti-gun. She's not good at moving large quantities of mass at once, so would struggle greatly lifting a tank even if touching it. Magneto is much larger scale than her, but she has other advantages over him in close range against smaller objects. She's super duper versatile, but drop a bridge on her and she's done for.

Donny could only realistically win if he snuck an explosive somewhere she doesn't notice, but he'd likely be super dead before that happened as she'd be railgunning him to pieces while deflecting his bullets. Pepper spray could also work well against her to negate her ability but obviously far too difficult to deliver that attack successfully.