Ability · Gen 8 · 2 Pokémon
Cotton Down
If this Pokemon is hit, it lowers the Speed of all other Pokemon on the field 1 stage.
When this Pokemon is hit by an attack, the Speed of all other Pokemon on the field is lowered by 1 stage.
Cotton Down was introduced in Generation 8. 2 Pokémon and forms can have it.
Pokémon with Cotton Down
As a regular ability (2)
Gossifleur
EldegossCotton Down FAQ
What does Cotton Down do?
When this Pokemon is hit by an attack, the Speed of all other Pokemon on the field is lowered by 1 stage.
Which Pokémon have Cotton Down?
2 Pokémon and forms can have Cotton Down: Gossifleur and Eldegoss.
Effect text from Pokémon Showdown (MIT); which Pokémon have it from Showdown's Pokédex, cross-checked against PokéAPI. Unofficial fan site.