Pokémon Season 1 Episode 43

Entering Neon Town, a bustling Metropolis where everyone is tired and rude, Ash and his friends find a Jigglypuff who is too shy to sing its hypnotic song. Realizing they can kill two birds with one stone, Misty tries to teach the Jigglypuff to sing while Team Rocket attempts to record the song so they can use it against Ash.