Pokemon Season 1 Episode 54 - The Case of the K-9 Caper!

⁣When Ash and his friends see a group of Growlithe training against a
Policeman posing as a robber, Ash decides for him and Pikachu to do the
same training to get the best they can be. However when Team Rocket
comes to steal them, Officer Jenny, Ash and the gang's voice gets mixed
up, causing the Growlithe to thinks that Team Rocket are the Officer
Jenny as they uses their ears to do command.