Slowking definitely. The entire slow evolution family are amazing. Slowking is a defensive for special defensive swap of slowbro, and we all know how amazing slowbro is. They learn all the same moves, will slowbro is better, slowking can still tobybro. Calm mind, slack off, surf/psychic, thunder wave. That is the most feared set in RBY. Slowking can use calm mind better, or worse, depending on how you see it, because slowking is specially defensive built, and calm mind boosts all the specials by one stage.