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This book follows the plots of the anime episode Odd Pokémon Out. In this book, it shows how Grovyle evolves but loses the ability to attack.
Ash and his friends reach Crysanthymum Island, and they all let their Pokémon out to play. Ash's Donphan, in particular sees some Rhydon rolling a grass ball down a hill. Donphan picks up the ball with his trunk, wanting to play with them, but the Rhydon's parents and many others think Donphan is trying to hurt their kids. They start a mad chase and Ash, along with the others, see Donphan running from all of the Rhydon. Max simply cries, "Stampede!" and they all run. Then, a truck pulls up. Nurse Joy gets out of the truck, sending out Meganium. She commands Meganium to use Growl, and Meganium obeys, causing the Rhydon stampede to go back to a normal state. Nurse Joy asks if everyone's Pokémon are okay, and everyone checks their Pokémon for scratches and wounds. Then Ash suddenly realizes Grovyle is gone. Nurse Joy says to get in her truck, and they all get in. Nurse Joy drives around, and they soon find Grovyle leaning against a tree. Ash sees another Pokémon in front of Grovyle. He looks at his Pokédex, which explains the Pokémon is Tropius. Ash knows Grovyle will fight Tropius, worried because of the size difference.