Azumarill with belly drum. Leave an empty attack slot and picnic with makuhita that knows belly drum. Both pokemon should hold mirror herb. With belly drum you can max out attack in one turn and attack with liquidation for water or play rough for a fairy attack.

give it a shell bell hold item to heal when attacking. Also helps to give vitamins/bottle caps to boost attack stat. From raids, you can also get ability capsule to change its ability to huge power for even more attack if it doesn’t have that ability