The Fairly OddParents (2001)

Season 6: Episode 11

Poof is trying to get the hang of shape shifting but unfortunately he takes after Cosmo! And worse, one of his attempts has him crash landing in front of the Turner house, where Mom and Dad find him and become convinced he's an alien super baby they need to raise to fight for truth and justice! But Timmy can't just steal Poof back because Mom and Dad have fallen in love with the little guy, so he must devise another way of getting Poof back to Cosmo and Wanda before Dad's attempts to turn the baby into a super hero get them all in trouble!