The only Ground immunity that isn't ground itself — and a movepool powerhouse.
Flying rarely appears as a primary type — most Flying-types are Normal/Flying, Bug/Flying or Dragon/Flying — but its secondary typing is more common than any other. The reason is that Flying gives free Ground immunity, resists Fighting and Bug, and unlocks the best priority move in the game: Brave Bird.
Flying is almost always bolted onto another type to plug weaknesses. Landorus-T, Dragonite, Corviknight and Braviary all use Flying as defensive utility more than offensive identity. Tailwind setters (Tornadus, Pelipper) are VGC staples for team-wide speed boosts.
Brave Bird (120 BP recoil) is the physical nuke. Hurricane is the 110 BP special option with 30% confusion chance. Acrobatics doubles in power when the user has no item. Roost is the standard Flying recovery move.
Pokémon Sword & Shield's Corviknight was the first Flying-type ever to become a 'ride Pokémon' for in-game fast travel, replacing the Flying HM that had existed since Red & Blue.