Pokemon - episode 60 - 26 Aug, 1998

On their way back to the mainland, Ash accidentally runs into a Wartortle that is trying to help its king Blastoise, a ruler of a small island that will not awake from its slumber. Squirtle dons his old persona as head of the Squirtle Squad to solve the case. It turns out Jigglypuff is stuck in one of Blastoise's blasters, singing it's lullaby, which has caused the Blastoise to fall asleep. (Source: Wikipedia)