While on the way to May's next contest, Ash and friends must stop at a nearby island to switch to ferry to the next island. They let their Pokémon out to play and Donphan, still as playful as ever, tries to play with some Rhyhorn, only to be chased by their parents. After being saved by Nurse Joy and her Meganium, Grovyle gets into a conflict with a wild Tropius and beaten badly. Meganium heals Grovyle and Grovyle falls in love with her. However, Meganium and Tropius love each other! Now Grovyle decides to battle Tropius again to get revenge and win Meganium's love!
The gang goes to Chrysanthemum Island. They will be redirected to Camomile Island, where they will go to Chrysanthemum Island. The heroes see a lot of Pokémon, so they decide to bring their own. Donphan sees a wool ball that came to it and 3 young Rhyhorn. It goes to play with them, but the Rhyhorn run away. 3 older and stronger Rhyhorn appear, so Donphan runs away. Seeing Donphan and the Rhyhorn, the heroes and their Pokémon run away as well. Suddenly, Nurse Joy comes and sends Meganium. Meganium growls, keeping Rhyhorn calm. The heroes thank them (though Brock flirts with her and is being pulled by Max).
Joy asks if the Pokémon are okay, so Ash confirms this. He does not see Grovyle, but turns and sees him with a Tropius. Joy tells that Tropius attacks anyone who approaches its tree, including Grovyle. Grovyle uses Quick Attack, but Tropius uses Steel Wing, knocking Grovyle. Tropius uses Gust, pushing Grovyle to the ground. Ash goes to Grovyle, who is attacked by Razor Leaf. Meganium uses Razor Leaf on Tropius, attacking it. Meganium reasons with Tropius, who calms down.
However, Grovyle is badly hurt, so everyone goes to the Pokémon Center. Team Rocket sees them and Meowth tells Jessie and James Tropius would make a breeze for the boss on hot days, eat the treat Tropius carries and promote them all if they were to capture it. It will be tough to capture it, so Jessie and James tell Meowth he might talk to it. Meowth uses a loudspeaker and tells he will get everything for Tropius what it wishes. Meowth tells Jessie and James Tropius will come with them if Nurse Joy's Meganium comes as well. He says that Meganium and Tropius are in love, so Jessie and James are convinced to capture Meganium as well.
At the Pokémon Center, Meganium heals Grovyle. When Grovyle wakes up, he sees Meganium and blushes. They are surprised by the reaction. Brock believes Grovyle fell in love, so Grovyle pretends he is hurt. Brock tells that Grovyle is feeling ashamed during the battle with Tropius. The heroes go out to give Grovyle rest, but after that, Grovyle stands up. Team Rocket is in machine and destroy a part of the building to get Meganium. Team Rocket recites their motto, though Mime Jr. replaces Meowth, so Meowth is angry. Anyway, Team Rocket wanders off, so the heroes follow them.
Meanwhile, Grovyle is, again, going to battle Tropius. Tropius begins with Gust and follows with Steel Wing, attacking Grovyle. Next, Tropius knocks him down with Razor Leaf and continues to do so. Grovyle spots the flower in its mouth, reminding him of Meganium, so uses Quick Attack to get onto the tree. Tropius searches and is attacked by Bullet Seed. Grovyle defeats him with Razor Leaf. Team Rocket comes with Meganium, seeing Tropius down and Grovyle up. Meganium charges and so does Grovyle, but Meganium passes Grovyle to see Tropius. Tropius is being healed by Meganium and stands up. Grovyle sees the couple in love and falls down in despair.
The heroes return, blaming Team Rocket for what happened to Grovyle. They tell Meganium is in love with Tropius, not Grovyle. So, they understand now that Grovyle wanted vengeance on Tropius and won. Brock tells Grovyle won the battle, but lost her love. Nevertheless, Team Rocket steals Meganium and Tropius. Grovyle is mad when he sees Meganium taken and evolves into Sceptile. Sceptile charges, so Jessie sends Seviper and James his Cancea. Meowth presses a button, sending Cacnea and Seviper to Sceptile. Sceptile uses Bullet Seed, but for some reason, fails. Sceptile charges with Leaf Blade, but fails again. Seviper uses Poison Tail and Cacnea Needle Arm to attack Sceptile.
The machine goes to stomp on Sceptile, but Pikachu uses Thunderbolt, crashing the machine. Meganium and Tropius are free and unhurt. Meowth presses a button to get the balloon down so they can get out. However, Tropius uses Gust and Meganium Razor Leaf, blasting them off. Tropius and Meganium are re-united once more. Joy tells them they are going to leave together, so Brock flirts with her, though Max pulls him away. Ash is worried what might happen to Sceptile, as he couldn't attack. Joy tells him Sceptile will be okay in physical meaning, but he cannot heal his broken heart so easily, but given time, he will. The heroes leave the island to May's next Contest.
- This episode's name is a pun to "Odd one out".
- This is one of few episodes where Cacnea does not hug James.
- Referring to Sceptile, Ash says "...he won" and "he lost..." which wasn't present in the Japanese version. In fact, Sceptile's gender has yet to be confirmed in the Japanese anime.