"That f-cking bird that I hate." -Dashie
Originating from the application Nintendo DSi Sound bundled with its titular device, the Parakeet's primary role is to repeat given audio in each of its appearances.
Super Mario Maker
In its inclusion in the game Super Mario Maker, he is able to be put in a level using the Soundfrog option and can repeat a sound received via the Wii U Gamepad's microphone; if the level is uploaded online, however, the clip is replaced with a generic tweeting sound.
Additionally, the Parakeet also plays a role in the title screen of said game. If the "I" of Super Mario Maker is tapped, the bird flies down from the top of the screen to rest on this letter for a limited time. If the Gamepad's microphone is used during this time, the Parakeet will repeat the sounds it has picked up using high- or low-pitched filters.
Dashie and "The Bird"
This Parakeet is often known to surprise or startle Dashie in the middle of playing one of his levels - not helped by the fact that many fans have noticed this and are taking advantage of this fact - but Dashie's interactions with the title screen are arguably more well-known. In one Mario Maker video he is shown to be interacting with the title screen and unknowingly utters a snarky phrase as the bird is perched upon the "I". When the Parakeet talks back to him, he is taken aback with amazement, stating that this blew his mind.
Soon after, he makes a habit of having his words spoken back to him, and the resultant deep filter that may be put on his voice began Dashie's weekly running gag, where he converses with Satan before his Mario Maker gameplays.