Bye Bye Psyduck (さよならコダック！またきてゴルダック？ Goodbye Psyduck! Come Again Golduck?) is the 11th episode of Pokémon: Adventures on the Orange Islands.
Ash and Co. arrive at Kinnow Island and meet a girl named Marina, who was just as crazy about Water-type Pokémon as much as Misty. They noticed that Misty's Psyduck's tail had begun to glow, meaning it was a sure sign it was ready to evolve. During a battle between Misty and Marina, a Golduck appears out of nowhere and Misty immediately thinks her Psyduck has evolved. After a battle with Team Rocket, when she called Golduck back, her Psyduck popped out, revealing that it never evolved so Misty realises she is stuck with Psyduck.
The heroes have a relaxing day at the beach. Psyduck sleeps on Lapras' back and when Lapras goes away, Psyduck fell in water and drowns, still asleep. Suddenly, Pikachu makes a fuss and Misty realizes Psyduck is gone. A woman fishes along with Tentacruel and sees a Psyduck emerging from water that cannot swim. The gang's Water Pokémon were sent, but they did not found Psyduck. Ash calls Lapras back and sees this was not easy to get rid of Psyduck. Misty gets riled up, as they need to continue searching for Psyduck, but Ash gets her confused by responding that she suddenly cares about it. Tracey believes it is love, thinking Psyduck is her favorite Pokémon Misty denies it, but they see a woman, whose Tentacruel carries Psyduck, with a pink tail.
The woman meets the gang, whose name is Marina. Seeing Psyduck's tail, Marina heard with a color like that Psyduck will evolve soon. Ash remembers that Psyduck evolves in a Golduck, causing Misty and Marina to be amazed by this discovery. Misty and Marina hear that they love Water Pokémon and have a conversation, making Ash, Pikachu and Tracey baffled. They show each other their lures and think of capturing the Legendary Pokémon. Marina asks Misty how come Psyduck cannot swim (making Ash and Tracey wonder about it, too). Misty is nervous, but responds that trait is what causes Psyduck to be rare, plus she wants it to trade for Tentacruel. Marina has a doubt about that, but proposes a battle to see which trainer is better. Misty accepts this challenge.
Team Rocket try to find the twerps, but do not know where to look. Meowth tells Jessie to let him see, but gets pounded. James asks if they can at least have lunch, but Jessie does not want to, wanting to find those twerps. Suddenly, she sees them, as they are about to have the battle. Marina proposes a 3-on-3 battle and Misty accepts. Marina sends Tentacruel and Misty her Goldeen (with Marina acknowledging her cuteness). Tentacruel goes to wrap Goldeen, but Goldeen responds using Agility. Goldeen goes to use Horn Attack, but gets defeated by a Poison Sting. Misty calls Goldeen back and sends Staryu. Marina and Misty compliment Staryu, so Ash asks if they are going to talk all day. Staryu uses Swift, immediately defeating Tentacruel. Marina sends her strongest Pokémon, Psyduck, much to the heroes' surprise. Staryu uses Water Gun, but Psyduck uses Confusion to reflect it to Staryu. Misty calls Staryu back. Marina proposes to send Psyduck, since it will evolve soon. Misty agrees and sends it, but...
...but the Poké Ball is empty. Ash goes to search in Misty's backpack, but cannot find it. He throws it to Misty, but misses. Misty goes for her back and gets it, but upon taking it, she sees Golduck. Misty is delighted to see it and hugs Psyduck, thinking nobody will say any bad things to it. Tracey knows this is love, as Psyduck loved Misty back. Meowth tells they can grab Golduck and Pikachu, so Team Rocket proceed. Psyduck uses Confusion to make a wave. Golduck uses Confusion and rides the wave, but Psyduck begins to spin around, as Team Rocket appear from the submarine. They engulf the heroes with a wave and capture the Pokémon. Team Rocket think it is better to capture the Pokémon without the motto, but see they caught a Psyduck and a Tentacruel.
Misty sees Golduck is fine, although Marina has got her Pokémon captured by Team Rocket. Marina sends Starmie, who goes with Golduck to save the Pokémon. Team Rocket argue whose fault it was for capturing these Pokémon, but seeing Golduck, they go to capture it. However, Golduck uses Confusion, controlling the submarine, causing the submarine to crash. Marina demands her Pokémon, so Jessie and James tell she can have it. Meowth stops them, as they need to trade Pikachu for these Pokémon, making Jessie and James admire his intelligence. Pikachu goes to electrocute them, but Ash warns him if he attacks, Marina's Pokémon will get shocked. Marina asks her Tentacruel and Psyduck if they can get out. They cannot, as Misty worries they have been exhausted, so Marina goes to save them herself.
Jessie sends Arbok, but Marina does not back down. Arbok goes to attack, but Golduck pushes it using Water Gun. Arbok uses Poison Sting, but Psyduck reflects the attack, then uses Confusion to blast it off. Using Hyper Beam, Golduck blasts off Team Rocket. Marina asks what happened to her Pokémon and sees Golduck returning with them. Seeing Golduck's awesomeness, Misty hugs it once more. Marina and Misty go to finish the battle. Golduck uses Fury Swipes, but gets tackled by Starmie, then hits it using Bubble. Golduck gets ready to use Hyper Beam, but Starmie uses Light Screen to counter it. However, the beam was so powerful, the Light Screen shattered, leaving Starmie to get hit and defeated. Marina congratulates Misty, who likes Golduck evolved. Tracey, Pikachu and Ash clap for her.
Misty goes to send Golduck back, but surprisingly, Psyduck comes out. Misty is confused how this happened. Golduck hears some girls and goes to them, posing and making them impressed. Misty is depressed by this revelation. They ask where was Psyduck and Tracey believes it was resting in its Poké Ball. Misty asks about the pink tail, but Marina seems to know that was not a truth. Tracey tells Misty that Golduck got her fooled. Misty responds with a glare, but gives up. Marina tells Misty that she handled a wild Golduck, which was impressive. However, Ash tells she did not win the battle, as Golduck was not her own. Tracey thinks he was wrong about the love explanation, as Misty gets riled up with a headache. The heroes depart on Lapras and say goodbye to Marina.
- "It's just a Pokémon version of Brock." - Misty about the wild Golduck
- This was the episode that premiered worldwide the special Mini-Misty Lure.
- Brock was mentioned by Misty in this episode because the Golduck she thought was her Psyduck evolved liked to flirt with girls, but unlike Brock, the Golduck is successful at flirting.
- The "Who's that Pokémon?" in this episode is Mewtwo.