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Iron Head is really just for M-Diancie and weakened Tapu Bulu, but Fighting has so few answers to those two (Lucario aslo comes to mind) that Iron Head or even Poison Jab is pretty much required (at least on a Scarf set).
(On phone, so excuse the autocorrects, if any)
Scarf Terrakion outspeeds any Staraptor and KOes it with Stone Edge, while Cobalion has good physical bulk and can use Thunder Wave to slow down those pesky theats, making it much easier for Fighting to handle.
Niche options include Focus Sash...