• English / United States: Misty's Psyduck
• Japanese / Japan: カスミのコダック
• Japanese (Romanized) / Japan: Kasumi no Koduck
• Japanese (TL) / Japan: Kasumi's Koduck

While investigating the disappearance of missing children in Yoyoyo Town, Misty came in contact with a wild Psyduck that Nurse Joy was treating at the Pokémon Center. Psyduck had a headache and Nurse Joy wasn't sure why it hadn't recovered like the other Pokémon. Brock said he'd help Nurse Joy with Psyduck but one look at it and Brock tried to pass the responsibility off to Misty because she was a Water Type Pokémon Trainer. A Poké ball fell out of Misty's bag and Psyduck pressed the button on it and and caught itself.

Misty and her Psyduck have a love/hate relationship as it often comes out unannounced much to Misty's dismay. Initially Misty was doing her best to get rid of it but time after time, Misty's Psyduck proved to be a charming and a powerful Water Pokémon which made it hard for Misty to get rid of it.

Sekichiku Gym

While at the Sekichiku Gym, Rocket Gang showed up and started to cause a ruckus. While Misty was about to send out her other Pokémon to battle them, Misty's Psyduck popped out instead and Misty finally relented and decided to get it to battle Rocket Gang. With the help of Ash Ketchum's Zukan, Misty learned its first four moves. It's Scratch attack missed hitting Jessie's Arbok but Misty's Psyduck ended up getting a headache from the pressure caused by Jessie's Arbok biting its head. Psyduck then unleashed its powerful combination attack of Disable and Confusion which actually made Rocket Gang unable to move and then float in the air and then caused them to swinging back and forth against the walls of the room. Ash Ketchum's Zukan noted that when Koduck's headache gets intense, they will use mysterious powers. Koga and Aya were both impressed with Misty's Psyduck and Koga wanted to trade his Morphon for it while Aya wanted to trade her Kongpang for it. Koga was almost willing to give it the Pink Badge for its help in dispensing Team Rocket. Misty though realized her Psyduck was more powerful than she had initially thought and decided that she wouldn't trade with either of them.