At the Fennel Valley Pokémon Center, Ash is practicing attacks with his Pokémon while Brock is excited to be cooking with Nurse Joy. His excitement quickly disappears when he finds Nurse Joy unconscious on the floor. They put her in bed, and Professor Oak says she needs rest. Meanwhile, Team Rocket is incredibly lost from when Harley sent them blasting off, and to choose their path, Jessie throws a stick that hits several Pokémon and damages a small bus passing on the road below.

The bus belongs to a Pokésitter named Matt, who is looking after several Pokémon. Ash, Brock, Professor Oak, and Scott go to pick him and the Pokémon up. Scott tows the bus back while the kids take care of the Pokémon, but a Bagon runs off and Ash and Matt are unable to catch it. The rest of the Pokémon are brought to the Pokémon Center where May and Max look after them, including a Larvitar that likes to use Sandstorm.

Ash and Matt see the Bagon jump off a cliff and fall into a raging river where it is then attacked by Carvanha. Ash has Pikachu and Sceptile help, with the Bagon eventually falling into Matt's arms. Unfortunately, the adventure has made Bagon sick. They bring it back to the Pokémon Center where Professor Oak and Brock attempt to make it well. While the other kids wait, Team Rocket comes in disguised as "assistant Pokésitters" and steals all the other Pokémon. They take off in their balloon, but Larvitar brings them down with a Sandstorm.

Back at the Pokémon Center, Bagon has gotten worse, but Nurse Joy is better. She manages to heal Bagon, and Scott fixes the bus. As Matt prepares to leave with the Pokémon, the kids say goodbye, while Ash receives some good news—Brandon has returned, so Ash can have his rematch.