On Mandarin Island, Pikachu and Togepi act strangely, and run away from their masters along with some other Pokémon. When Ash complains panickedly to an Officer Jenny (who has an annoying Gastly), she says that a lot of Pokémon have been running away from or even turning on them. Everyone speaks to Professor Oak via videophone (strangely, Tracey doesn't wig out, he's an Oak fan) and Jenny suggests that a psychic Pokémon might be causing the disturbances, and that's why Gastly isn't affected.
Meanwhile, Meowth runs away from Jessie and James, but they chase after him and find themselves in a warehouse with Butch and Cassidy! The four Rockets compete with mottos, and then when JJ go to fight, a Drowzee shows up, attached to a special machine, which enables it to take control of their Pokémon! Their Pokémon, even Meowth, attack them, and Officer Jenny and company find the duo lying unconscious on the street. After some urging, Jessie and James, who feel really bad/unhappy that their Pokémon are gone, decide to help (because other trainers feel the same way, and they want revenge too ^_^.).
Jessie and James sucker their way back into the warehouse, sneaking Ash-tachi with them. Drowzee has all the Pokémon combine attacks, and Gastly tries to fend them off, while Pikachu attacks Ash. Ash lures Pikachu to shock him *and* the machine, which destroys the whole operation, leaving Drowzee's psychic powers useless to control the others. All the Pokémon are freed, but Butch and Cassidy still want to fight. Arbok, Weezing and Pikachu are used, but in the end...
Drowzee uses Metronome, waving its fingers. Togepi smiles and mimics the motion... and then, a huge explosion is caused... nobody knows about this hidden power, as Drowzee was about to attack and they must have assumed it was its fault. Butch and Cassidy are carted off to gaol again, and everything works out peachy.