As Team Rocket trudges through Sinnoh, they run into the Magikarp Salesman who's tricked them so many times before. This time, he cons them into buying an Evolution machine that will evolve a Pokémon at any time—or so he says. Elsewhere, Ash and his friends hear about the B-Button League, a group of Coordinators who never evolve their Pokémon. The rumors say they have a beautiful Feebas and a powerful Magikarp, so Ash and his friends go to check it out.
The B-Button League is headed by a girl named Haley, and she and her sister Oralie do indeed have a very fine Feebas and Magikarp. Team Rocket sneaks in to watch Dawn and Ash test their Pokémon against Oralie's Magikarp; not only does Magikarp defeat Piplup, it's strong enough to give Pikachu a run for its money! Team Rocket is so impressed, they grab Magikarp and Feebas on the spot, then take Pikachu too when it tries to stop them.
Now Team Rocket prepares to use their new machine to evolve all three Pokémon, much to our heroes' dismay. But the Evolution machine doesn't work at all! However, Team Rocket has a plan B: their new machine can also transform into a tough-looking robot. Too bad for them that the robot quickly falls apart, being just another sales scam. Oralie and Haley have Feebas and Magikarp help Pikachu defeat Team Rocket, and then our heroes can happily continue on their way to Floaroma Town!