Generation Vii
Tangling Hair
Contact with the Pokémon lowers the attacker’s Speed stat.
Detailed Effect
When this Pokémon takes regular damage from a contact move, the attacking Pokémon's Speed lowers by one stage.
Pokémon With Tangling Hair
2 canonical Pokémon forms can have this Ability.
Alolan Diglett 
Alolan Dugtrio