Not any physical attack, any attack that makes contact. That excludes moves like Earthquake, Stone Edge, and every special attack but Grass Knot and Infestation (Bane of my Tough Claws Mega Aerodactyl, let me tell you). Iron Head is boosted, though. Personally, I would still go with Meteor Mash because of the potential Attack boost and the fact that it averages at slightly more damage per turn (90 power*90% accuracy=81 power on average vs Iron Head 80 power*100%accuracy=80 power on average. Minute, yeah, but it's something). But either one is a viable choice, and depending on how much that flinch chance means to you (and you luck), you might want to go with Iron Head over Meteor Mash anyway.