The first appearance of Birdo is in Super Mario Bros. 2, where she appears as a boss character in many levels, serving the wicked villain Wart. Birdo comes in three colours. As gray in World 7-1, Green Birdo also appears in the NES version.
Birdo generally walks back and forth, facing the player character and spitting three projectiles at a given time. To defeat her, the participant must jump onto her eggs or a different thing and throw them back at her. However, if Birdo is green, the player is needed to throw Mushroom Blocks instead. Birdo often holds a Crystal Ball, with two exceptions: Pink Birdo's look as a typical enemy in World 4-3, and a Red Birdo area in World 7-2, in which Birdo relinquishes a key needed to get into the Mask Gate resulting in Wart. It's worth noting that Birdo only is shown physically holding the ball in the NES version of Super Mario Bros. 2; in Yume Kojo: Doki Doki Panic, she drops it out of nowhere upon defeat, while in remakes of Super Mario Bros. 2, it awakens from her snout upon defeat.
From the Satellaview special BS Super Mario USA, Birdo first received a speaking role, even though it is mostly lost due to the broadcast nature. Taking place sometime after Super Mario Bros. 2, the pink Birdo and her red and green friends, now depicted as different characters, again function Wart and invade Subcon. Birdo is fought in the identical way as in the predecessor, though this time Birdo may seem randomly and invincibly fly at the player. She can throw ones that are larger and can throw numerous eggs in the air. Like Wart and Mouser, Birdo appears often as a card on the display and can cast spells to switch the player character or transform enemies into bombs. In the end, Birdo and her companions lose again against Mario and friends, even though it is said they would get better treatment in the future. The voice actors for Birdos, and her friends are all okama, a Japanese term for men who dress and act like females, bettering the franchise-long running joke about Birdo's ambiguous gender.
Birdo, known in Japan as Catherine , is a recurring character in the Mario franchise. Her first appearance was as an enemy in Yume Kōjō: Doki Doki Panic, which was rebranded as Super Mario Bros. Since that time, she's appeared in various spin-off series of the franchise, and her first role as an antagonist has slowly been scrapped in favor of a newer function as an ally. Birdo has also been merchandised into figurines, plush toys, and amiibo cards.