Keen Eye
Was going to go with Justified, but then I realized I don't think of Tomohawk as a righteous fighter like Lucario, Gallade, and the (4?) Musketeers. Also Big Pecks is terrible IMO, for several reasons mentioned earlier. So I went with the ability common on tons of Fighting types, and "Birds of prey" Flying types: Keen Eye.
Was going to go with Justified, but then I realized I don't think of Tomohawk as a righteous fighter like Lucario, Gallade, and the (4?) Musketeers. Also Big Pecks is terrible IMO, for several reasons mentioned earlier. So I went with the ability common on tons of Fighting types, and "Birds of prey" Flying types: Keen Eye.