4 Atk Swanna Brave Bird vs. 0 HP / 4 Def Primeape: 348-410 (128.4 - 151.2%) -- guaranteed OHKO
252 Atk Primeape Close Combat vs. 0 HP / 0 Def Swanna: 123-145 (42.2 - 49.8%) -- guaranteed 3HKO
It can switch in twice at least (w/o Rocks).
252 Atk Primeape U-turn vs. 0 HP / 0 Def Swanna: 48-57 (16.4 - 19.5%) -- possible 6HKO