Curious Medicine
When the Pokémon enters a battle, it scatters medicine from its shell, which removes all stat changes from allies.
Own Tempo
The Pokémon sticks to its own tempo, preventing it from becoming confused or being affected by Intimidate.
It administers its potions to weakened Pokémon it sees. These potions are derived from poison and secreted from holes in Slowking's horns.
It creates potions by mixing toxins with the food it's eaten. Not even Slowking itself knows what effects the potions will have.