Oblivious
The Pokémon is oblivious, keeping it from being infatuated, falling for taunts, or being affected by Intimidate.
Own Tempo
The Pokémon sticks to its own tempo, preventing it from becoming confused or being affected by Intimidate.
When a Slowpoke went hunting in the sea, its tail was bitten by a Shellder. That made it evolve into Slowbro.
If the tail-biting Shellder is thrown off in a harsh battle, this Pokémon reverts to being an ordinary Slowpoke.