This episode was originally scheduled to air on November 15, 2007.
Throwing the Track Switch (Japanese: エイパムとブイゼル！それぞれの道！！Eipam and Buoysel! Respective Roads!!) is the 55th episode of the Diamond & Pearl series, and the 521st episode of the Pokémon anime. It first aired in Japan on November 22, 2007 and in the United States on April 26, 2008.
When Dawn and her friends run into Zoey on their way to Solaceon Town, the two Coordinators can't resist having a practice battle. At the same time, Ash has Chimchar and Aipom battle each other to train for his upcoming Gym battle. But Buizel is distracted by the battle between Chimchar and Aipom, while Aipom keeps trying to watch the Contest battle between Buizel and Zoey's Glameow. It seems as if Buizel would rather be battling while Aipom would rather be in a Contest, so Zoey makes a bold suggestion: why doesn't Dawn trade Buizel for Ash's Aipom?
Dawn and Ash aren't sure if that's a good idea. To test the waters, Ash suggests that he use Buizel to battle Brock, and Dawn can use Aipom to battle Zoey. But before the battle can get very far, Jessie and Meowth show up in disguise. James is miserable now that Cacnea's gone, so his teammates are determined to cheer him up-by stealing Aipom and Buizel!
But James, unaware of the plan, accidentally blows Team Rocket's cover. Seviper uses Haze and Team Rocket makes a grab for Aipom and Buizel anyway, but they end up snagging Glameow and Sudowoodo instead. Ash and Dawn use Aipom and Buizel to defeat Team Rocket, and it looks like Ash's attacking style is a good match for Buizel while Aipom's flair is a good match for Dawn. They complete the Pokémon trade, then get back on the road to Dawn's next Contest!
Inside the Center, Dawn and Aipom watch the television, which shows Kenny winning his second Ribbon in Sage Town with the help of his Prinplup. Zoey enters the Center and greets them, before noticing Ash and Pikachu spread out across a bench, feeling too full of food to move. While Brock and Sudowoodo make a herbal remedy for them, Dawn glances at her only Ribbon, upset that Kenny is passing her. Ash gives her encouragement as Marian announces that the next Pokémon Contest will be held in Solaceon Town, which Zoey mentions is en route to Veilstone City. With this information, Dawn decides to train for the Solaceon Contest, asking Zoey if she is entering as well, but Zoey decides to pass in order to improve one of her combinations. Still, Dawn asks to train with her tomorrow, which she agrees to. Brock and Sudowoodo finish making the herbal remedy for Ash and Pikachu, which they both find disgusting, causing them both to run around the room in disgust.
The next morning, Dawn decides to prepare Buizel for his Contest debut by having a practice Contest Battle against Zoey and her Glameow. Ash is also inspired to train, deciding to practice with Aipom and Chimchar. While Brock studies Ash's battle, Dawn commands Buizel to use Water Gun. Glameow uses Iron Tail to dissipate the attack into a fine mist sparkle, which looks appealing. Aipom watches a little too intently and does not hear Ash's first command, but quickly gets back into battle. Brock notices Aipom’s behavior as they try to get back on track. Dawn critiques Buizel's Water Gun, as it made only Glameow look appealing. As Buizel tries to get into the Contest flow, Ash tells Aipom to use Focus Punch, which Chimchar easily dodges. The battle grabs Buizel's attention, which Zoey notices. Dawn gets Buizel's attention back and has him use Aqua Jet. Glameow uses Shadow Claw in an attempt to counter, but ends up going over the attack, using the water mist to create another appeal before landing. Buizel lands and shakes off the water, which Dawn also critiques. Buizel tries to take it in, but drifts back to watching Ash's battle. Chimchar launches Flame Wheel as Aipom dodges and fires Swift, which Chimchar charges into. Zoey notices Buizel's interest as Aipom counters Flame Wheel. Aipom suddenly uses Swift towards the sky and jumps on the stars as a Contest move. Zoey notes the appeal as Dawn mentions that Aipom watches her train a lot. Ash and Dawn prepare to continue training, but Zoey stops both of them and brings up when she said Dawn should raise Aipom, pointing out that Aipom likes Contests while Buizel prefers battles. Zoey suggests that Ash and Dawn should trade Aipom and Buizel to each other, which surprises everyone. Team Rocket listens in nearby and decides to steal both Pokémon to help the depressed James.
Inside the Pokémon Center, Ash and Dawn watch as Nurse Joy helps two Trainers conduct a trade with a Ponyta and a Munchlax. As the trade finishes and the Trainers leave, Nurse Joy asks if Ash and Dawn are ready to trade. They hesitate, however, as they realize how much they have bonded with their Pokémon. Dawn knows Aipom has been with Ash a long time, while Ash knows that Dawn has already put time into training with Buizel. Joy mentions that Trainers need to adapt to their Pokémon in the same way Pokémon bond to Trainers. Ash suggests that he should have a practice battle with Buizel against Brock, while Dawn practices with Aipom against Zoey. Brock realizes that it will simulate the trade effects and if it will really work.
Outside, they prepare for the practice matches as Zoey sends out Glameow, while Brock chooses Sudowoodo. Before anything starts, however, a disguised Team Rocket, minus James, shows up as a fake Pokémon au pair service, where they train Pokémon for a Trainer. However, James shows up without a disguise, which destroys their plan. After realizing that they made their plan to help him, James comes round and has Carnivine attack alongside Seviper and Dustox. Dustox fires Psybeam and Carnivine uses Bullet Seed, the attacks hitting Ash and his friends. Seviper follows up with Haze, but Ash is quick to bring out Staravia to Gust it away. After reciting their motto, Team Rocket realizes that Carnivine and Seviper took Sudowoodo and Glameow instead of Aipom and Buizel, but prepare to steal them anyway. Ash and Dawn step in with their new practice partners to stop Team Rocket.
Carnivine fires Bullet Seed and Dustox uses Psybeam. Aipom uses Swift to create a giant shield to block the attack and demonstrate Contest appeal as well. Dustox uses Whirlwind, but Buizel hits Dustox with SonicBoom before knocking her out with Aqua Jet. Seviper fires Haze as Aipom uses Double Team to surround Buizel, before they all Focus Punch to disperse the Haze. Buizel fires Water Gun, finally sending Team Rocket blasting off. As Zoey and Brock hug their Pokémon, Ash and Dawn applaud their new partner Pokémon's abilities. Brock and Zoey mentions that it is a perfect match, which the Trainers agree to, so the trade is set.
At the Pokémon Center, Ash and Dawn place Aipom and Buizel's Poké Balls into the trade machine and pull the lever together, conducting the trade. After it finishes, Ash and Dawn pick up their new Poké Balls and summon their new Pokémon, Buizel and Aipom. Ash vows to use Buizel at the next Gym while Aipom will participate in Dawn's next Contest.
Pokémon senryū: カラナクシ にしとひがしで いろちがい Karanakushi, nishi to higashi de, iro chigai "Karanakushi, the Western and the Eastern are, alternate colored"
This is one of the few episodes Brock doesn't flirt with Nurse Joy, although earlier in the episode, while he was making a medicine for Ash, he said he wouldn't waste Nurse Joy's time when she could be working.