Pokémon : S3 | E40 – The Psychic Sidekicks!

Ash and his friends are walking through a wood, and notice a Trainer Tips sign that warns of Ghost Pokémon in the woods and recommends the use a Psychic Pokémon to keep them away. They don't have any Psychic types, but Brock remembers that Psyduck can use Psychic attacks. Misty releases her Psyduck and tells it to use its Confusion attack if they meet a Ghost Pokémon, but it doesn't seem to understand her.

The bushes rustle and something peeks out. Misty orders Psyduck to use Confusion, but it returns to its Poké Ball. Ash and Brock examine the creature in the bush, and comment that it doesn't look like a Ghost-type Pokémon. A girl walks up and says that it isn't, it's her Girafarig's tail. Ash consults Dexter and learns that Girafarig is a Psychic Pokémon with a second head on its tail.
(Source: Bulbapedia)