When Pokémon Worlds Collide (Japanese: ライバルバトル!三対三！！ Rival Battle! 3 VS 3!!) is the third episode Pokémon: Diamond and Pearl.
As Ash and Brock follow Starly, Dawn, Piplup and Pikachu run to meet them. Soon, Ash and Brock spot some sparks. It is the same man, whose Elekid attacks Starly. The man throws a Poké Ball, but the Starly is not captured, as it is Ash's. Ash and Brock apologize for the inconvenience and ask if he saw a girl and a Pikachu. The man did not and asks if his Starly is good enough. The man tells only the strongest ones are the best ones and sends three of his own Starly. He scans the Starly via his own Pokédex and releases two of them, as the third one knows Aerial Ace. Ash is very annoyed about his perspective and tells him any Pokémon is strong if it is trained. The man proposes a battle - 3-on-3. Ash is backed down, as he does not have Pikachu. The man is disgusted and goes away with his Elekid.
Ash wishes Piakchu to be near him and sees another spark. Pikachu uses Volt Tackle on Team Rocket's machine. Dawn demands why are they after Pikachu, so they respond it is very powerful. They use the robot arms to capture Pikachu, even if Piplup tried to stop them with Bubblebeam. Pikachu uses Thunderbolt, but with no effect. Piplup uses Bubblebeam, but also no effect. Piplup charges, but is thrown away by the robotic arm. Team Rocket taunts Dawn and Piplup, but not for long - Aipom uses Swift and Starly Whirlwind to stop them. However, a robotic arm attacks Ash, knocking him out. Ash stands up and goes to get Pikachu, but is stopped. However, he bounces off a tree and goes on a robotic arm and goes up. The robotic arms try to stop him, but one crashes into the robot. Ash tries to free Pikachu, but with little effect. Brock, Dawn and the Pokémon witness that the robot explodes and Team Rocket blast off.
From the scrap, Ash and Pikachu emerge. Pikachu meets Starly, Ash's newest Pokémon. Ash also thanks and meets Dawn. Ash thinks Piplup is injured, but Dawn convinces him otherwise. Soon enough, Piplup falls down and Brock sprays an concoction to heal it. Later, Ash, Brock and Dawn contact Prof. Rowan for the update. Rowan is pleased to hear the success and also tells Ash he got a package from his mom. Meanwhile, the man and his Elekid see the rubble from the Team Rocket's machine.
Dawn is told Brock is a breeder. He promises he will make food for Piplup, making Dawn and Piplup happy. Jenny comes on her motorcycle and heard the news. Brock flirts with her and this makes Dawn confused, but Ash tells it is a normal. At the lab, Ash sees he got new clothes, puts them on and contacts his mom. His mom is thrilled to see him and wanted to give him the clothes right away... if he did not rush out. Next, Ash contacts Oak to tell Pikachu is safe and introduce him to Dawn. Dawn knows Oak is a poet and wonders why is he on TV reciting poetry. Rowan comes and greets Oak and speaks with him in private.
Dawn asks why are Ash and Brock here - Ash wants to compete in Sinnoh League to become a Champ. Brock looks on the map that past the Jubilife City is Oreburgh City, where the first Gym is located. Dawn wants to come as well, as she wants to become a Coordinator and the first Contest is in Jubilife City. Ash, Brock and the Pokémon agree with her, so she can go with them. Ash returns his Pokémon, but Dawn wonders why Pikachu is not in the Ball. Ash tells Pikachu prefers to be on his shoulder. Ash thanks Prof. Rowan and they all go out, but they see the man again. The man introduces himself as Paul an wants to battle Ash, so they go to the backyard.
Dawn is excited to see a battle. Paul tells the offer is same - 3-on-3 battle. Ash sends Starly and Paul his own. Ash's Starly starts with Quick Attack, hitting Paul's. Paul's Starly retaliates with Aerial Ace, hitting Ash's. Ash's Starly uses Wing Attack, but Paul's uses Double Team and follows with Aerial Ace, hitting Ash's. Ash's Starly is defeated and they both call their Pokémon back. Ash sends Aipom and Paul his Chimchar. Aipom uses Swift, but gets countered by Ember. Aipom goes to use Focus Punch, but gets attacked by Flame Wheel. Aipom uses Double Team, but Chimchar banishes the illusions with Ember and follows by scratching Aipom. Aipom uses Focus Punch and Chimchar charges with Flame Wheel. However, Aipom dodges and defeats Chimchar. Ash and Paul call their Pokémon back.
Ash sends Pikachu and Paul his Elekid. Pikachu starts with Thunderbolt, but Elekid resisted it. Pikachu gets hit by Thunder and pushed away. Pikachu charges with Volt Tackle, but gets bounced off by Protect. Pikachu uses Iron Tail, but gets countered by Brick Break. Elekid uses ThunderPunch, but Pikachu evades and attacks it with Iron Tail. Pikachu gets wounded by Brick Break and with this, both Pikachu and Elekid fall down, resulting in a draw. Ash rushes to Pikachu and tells Paul won, as Pikachu fell first. Paul still sticks that it was a draw and releases Starly, as he wants a stronger one. Paul thanks Rowan and wanders off, ignoring Ash's another challenge.
- Jessie: "Listen, is that a voice I hear?"
James: "It's speaking to me loud and clear."
Jessie: "Floating on the wind."
James: "Past the stars."
Meowth: "In your ear."
Jessie: "Bringing Chaos at a break-neck pace."
James: "Dashing hope, putting fear in it's place."
Jessie: "A rose by any other name smells just as sweet."
James: "When everything's worse, our work is complete."
James: "And it's James."
Meowth: "Meowth, now that's a name."
Jessie: "Putting the do-gooders in their place."
James: "Team Rocket."
Meowth: "We're in your face."
Mime Jr. "Mime mime mime."
- Team Rocket debuts their new motto.
- Ash changes to his Diamond and Pearl series outfit.
- This episode originally aired as a 2-hour special with the first two episodes.