Hey joey. Made this RU team featuring Mega Bannette, defensive spikes cloyster and sub work up firium z swellow. Its fun but its also pretty effective.
https://pastebin.com/BPiiz2V1 . The goal of the cloyster and swellow combo is to lure in Registeel, here's a calc:
+1 252 SpA Swellow Inferno Overdrive (175 BP) vs. 252 HP / 252+ SpD Registeel: 214-254 (58.7 - 69.7%) -- guaranteed 2HKO after Leftovers recovery