This site has not yet been updated to reflect the changes in Reborn v19.5. It still only reflects the state of the game as of v19.16.
When the Pokémon is hit by an attack, it scatters cotton fluff around and lowers the Speed stat of all Pokémon except itself.
There are no Pokémon with this ability. (It's probably a Gen 8 ability that's snuck its way into the database by mistake.)