There's still a desert to cross before Ash can reach Veilstone City and the next Gym, but our heroes decide to let their Pokémon out to play in the sand. Pachirisu is right on top of a Hippowdon that surfaces from underground, and it falls right into Hippowdon's mouth! Hippowdon burrows back beneath the surface, so the chase is on to catch up with it as it pops in and out of the sand. Along the way, the gang runs into the Hippopotas they rescued a while ago. Is this Hippopotas looking for Hippowdon too?

Team Rocket is after Hippowdon too, but it'll take more than just a net to reel in a Pokémon this big and heavy. Unfortunately for everyone, the other Team Rocket, Butch and Cassidy, show up with a giant robot that ought to do the trick. Butch and Cassidy are out to grab a Hippowdon for Professor Nanba, but Jessie and James refuse to be outdone. It's not long before Jessie takes the controls of her mecha Slowbro and starts to slug it out with Butch and Cassidy's robot!

Ash and his friends try to lead Hippowdon to safety while the villains are distracted. Pachirisu is freed and Hippowdon wrecks Butch and Cassidy's robot with Hyper Beam, but then our heroes are caught between both Team Rocket teams! Hippopotas uses Yawn to put all the criminals to sleep, then joins forces with Hippowdon to send Jessie, James, Butch, and Cassidy far, far away. Now Hippopotas is happily reunited with Hippowdon and Pachirisu is back where it belongs!