In Red Rescue Team and Blue Rescue Team, and Explorers of Time, Darkness and Sky, Cloud Nine changes the weather to Clear upon entering a floor, and then every subsequent 36 turns. Cloud Nine will take precedence over Drizzle, Drought, Sand Stream, and Snow Warning. Additionally, this Ability prevents the use of the moves Sunny Day, Rain Dance, Hail, and Sandstorm, and the items Sunny Orb, Rainy Orb, Sandy Orb, and Hail Orb become useless (trying to use one will still consume the item). If the dungeon has natural weather, it will return when Cloud Nine's effect ceases.
In Pokémon Super Mystery Dungeon, Cloud Nine nullifies the effects of the weather rather than changing the weather to Clear. Abilities such as Drizzle, and moves such as Rain Dance will still activate, but the effects of the weather will remain negated.
The Japanese name of this Ability is a double entendre, written so as to suggest ノー天気 nō tenki (no weather), but also homophonous to 能天気 nōtenki (carefree, and also used as the word for the Lax nature), in reference to Psyduck, originally the only Pokémon (in addition to Golduck) that had this Ability. The English name derives directly from the "carefree" meaning, while still maintaining a weak pun to connect it to the weather.
