The Thief That Keeps on Thieving! (Japanese: ヤンヤンマ！ゲット作戦！！ The Yanma Capture Operation) is the 28th episode of Pokémon: DP Battle Dimension.
As the heroes continue their journey, Dawn is happy to see her second ribbon. Ash now wants his Gym Battle, but they stumble upon a Yanma. It flies over their heads, then departs. A boy comes and asks them if they saw a Yanma, so they point to the direction and follow the boy to find Yanma. The boy finds it and sends Pipi, his Piplup, who uses Peck, but misses. Yanma uses SonicBoom, hitting Pipi, so Pipi goes to use Pound, but misses and gets hit by Wing Attack. Yanma departs, leving the boy confused and sad. The boy tells he got Piplup as his first Pokémon and now wants to get that Yanma. The heroes introduce themselves to the boy, while his name is Tyler.
Dawn admires Pipi's tiara, which was a gift from Tyler's mom. Tyler tells his journey started about a week ago. He woved to get the first Pokémon he finds, which was Yanma. However, Yanma is very elusive, as he is chasing it for three days. Ash and Dawn remember well how much it took her to catch Buneary. So, the heroes lend help to allow him get that Yanma. The heroes search and Staravia found Yanma. Pipi uses Bubble, but misses Yanma, but manages to attack by pecking it. Next, Pipi pounds Yanma. Yanma counter-attacks with Quick Attack, but is canceled by Peck. Tyler is about to throw his Poké Ball, but Team Rocket, from their submarine, emerges. Jessie throws her Poké Ball and catches Yanma, then they return into the submarine and dive away. Tyler is sad to see that his Yanma got caught.
Pipi searched, but did not find Team Rocket. Tyler is depressed, but the heroes convince him to fight over it, to find a new Pokémon. Another Yanma passes by, so they go to get it. Team Rocket is very happy to have caught the Yanma and they walk pass a hill and give it to a Delibird, who goes to deliver it to the boss. The heroes search, though even Staravia couldn't find it, as it is getting darker. So, they set up a camp. Brock prepared the food and gives it to everyone. Ash and Dawn show Tyler their Badges and Ribbons, while also showing their Pokémon. As Team Rocket sleeps, in Team Rocket HQ Giovanni receives the package. The computer analyzes Yanma. Giovanni is told they got plenty of Yanma, so he thinks what to do with it.
In the morning, the heroes are about to go. Brock made some special food to lure Yanma. Team Rocket wakes up and gets a delivery from Delibird, from the boss. They see the Poké Ball and think there is a powerful Pokémon inside. They are surprised to see he sent Yanma back, but convince themselves it was a gift. As she caught it, they consider Jessie should have it. However, she fells that they ow now to the boss, so they decide to capture another Yanma. Pipi defeated Yanma and Tyler is about to throw his Poké Ball, but Team Rocket intercepts. Jessie sends her Yanma and Ash his Chimchar. Yanma uses Wing Attack, though Chimchar evades. Chimchar uses Flamethrower, making Team Rocket very angry, as Meowth uses Fury Swipes to attack Chimchar. James sends Carnivine, who uses Bullet Seed, along with Yanma, who uses SonicBoom.
Chimchar retaliates with Flame Wheel, hitting them both. Yanma uses AncientPower, hitting Chimchar and it evolves into a Yanmega. Yanmega uses SonicBoom, hitting the heroes at a rapid pace. Yanma that tyler wanted to catch departs, so Team Rocket call their Pokémon back and go into the submarine. As Team Rocket scout, Jessie sends Yanmega to help them, though it gets on her hair. James reads from his cards Yanma evolves only when it knows AncientPower, so they think the boss taught it before it sent it to them. So, they appreciate the boss' time and want to get that Yanma. Brock's lure worked, as Yanma eats his food. Pipi pounds Yanma, though Team Rocket emerges. Ash sends Buizel, who evades Yanmega's AncientPower. Buizel's Aqua Jet hits Yanmega, then uses SonicBoom to push it away. With Pikachu's Thunderbolt, Team Rocket blasts away, though they consider to send Yanmega to the boss, as it evolved.
Now, Tyler has his battle. Pipi uses Bubble, though Yanma evades. Yanma uses Wing Attack, but misses Pipi. Pipi pecks Yanma and swiftly evades Yanma's SonicBoom. Pipi uses Bubble and follows by pecking, knocking Yanma out. Tyler throws his Poké Ball, but Yanma comes out. Pipi uses Peck to knock it out again and Tyler throws his second Ball, this time catching it. Tyler is happy to know he finally caught that Yanma. Before they split, Brock gives Tyler some food for Yanma. They advise him to find some friends to help him in his journey. He departs, so the heroes continue their journey.
- This episode has a similar premise to the episode Wings n' Things, though in that episode the younger Trainer wanted to recapture Yanma.
- This is one of the very few episodes in which Team Rocket successfully captures a Pokémon for Giovanni, although he sends it back to them. However, Yanma was a wild Pokémon at the time of capture, so it hadn't been stolen.
- Before the second battle with Team Rocket, Tyler's Yanma is knocked out. However, at the end of the battle, Yanma is back at the food stand completely recovered.
- During the second battle with Team Rocket, Brock's food stand disappears.