Ash and co. have finally made it inside the Eterna gym. They notice that there's a lot of green grass and trees surrounding the place. Gardenia welcomes Ash to her gym. It's the day where Ash will finally be able to battle Gardenia for his second badge. Meanwhile, Team Rocket is outside the gym. Jessie and Meowth wants to dig underneath the gym and then steal Pikahcu. James doesn't think that the idea is very creative, but it's what Team Rocket does best. The battle with Ash and Gardenia is about to begin. The referee explains that three Pokémon will be used for the battle. When the referee is done explaining the rules, the battle begins.

Gardenia starts off by sending out Cherubi. Ash sends out Turtwig. Dawn and Brock notice that the Pokémon are even because they are both grass types. Turtwig uses Tackle, but Cherubi dodges it. Turtwig then uses Razor Leaf, but Cherubi quickly dodges each leaf. Ash notices that Cherubi is very fast. Gardenia states that the brighter the sun the faster Cherubi gets. The sun is very bright at the moment. Brock says that Cherubi has a special ability called Chlorophyll, which allows Cherubi to do that. Gardenia orders Cherubi to use Solarbeam. Cherubi uses the attack, but Turtwig dodges it. Ash knows that Solarbeam takes time to charge, so he orders Turtwig to use Razor Leaf. Gardenia orders for another Solarbeam attack. Cherubi uses the attack again, knocking Turtwig to the ground. Cherubi then uses Magical Leaf, but Ash has Turtwig sent back into its Pokéball right before the attack could hit. Gardenia noticed that Ash has changed. He would usually have his Pokémon battle to the end.

Team Rocket is digging their way underground. They end up digging themselves into an underground cave. They wonder where they are at. A man approaches Team Rocket, and Team Rocket says their motto. The man explains that he is an Eterna City explorer, and he hunts underground for treasure. He explains the different treasures and their values. Team Rocket's eyes light up. Team Rocket offers to help the man with digging up the treasure. The man accepts Team Rocket's offer.

Knowing that grass Pokémon are weak against flying types, Ash sends out Staravia. Cherubi begins the battle with Solarbeam. Staravia dodges the attack and then uses Wing Attack. Cherubi quickly dodges the attack. It begins to charge up for another Solarbeam, but suddenly the sun fades away behind the clouds. Without the sun, it will take longer for Cherubi to perform a Solarbeam attack. Gardenia isn't worried at all. She orders Cherubi to use Magical Leaf. Staravia flies high up into the air until the leaves break apart. Cherubi is out of range with Staravia, so Staravia has the advantage. Ash tells Staravia to fly down slowly. Ash notices the sun is moving away from the clouds and into the opening. Ash orders Staravia to use Wing Attack. Staravis charges for Cherubi. Cherubi tries to dodge the attack, but the sun gets in Cherubi's eyes. Cherubi is hit by the Wing Attack and is sent flying in the air. Then after a Quick Attack and Aerial Ace, Cherubi faints. Ash wins the round.

Gardenia's next Pokémon is Turtwig. Staravia uses Wing Attack. Turtwig dodges the attack. Ash tells Staravia to keep on using Wing Attack, but Turtwig dodges each one. Dawn and Brock think that Ash should change his strategy, but Ash ignores them. Gardenia soon realizes that Staravia is cornering Turtwig into a tree. Turtwig has fallen into a trap. Turtwig knocks into the tree, giving Staravia the chance to attack. Staravia strikes using Aerial Ace. Before Staravia can launch a second attack, Turtwig uses Leech Seed, followed up with a Tackle. Staravia faints.

Ash thanks Staravia for the great battle. He returns Staravia back into its Pokéball and then sends out Turtwig. Meanwhile, Team Rocket is busy digging in the cave with the man. The man sees a jewel fall from the digging. He examines it and states that it's a red sphere. Team Rocket keeps on digging, and the man gathers up all the treasures that are dugged out. Meanwhile, Ash's Turtwig uses Tackle, but Gardenia's Turtwig dodges the attack. Gardenia's Turtwig then uses Leaf Storm, an attack that Ash's Turtwig dodges. It begins to run around circles. Ash's Turtwig then charges towards Gardenia's Turtwig with Bite. Gardenia's Turtwig counters with Leech Seed. The seed plants itself right on Ash's Turtwig and begins to suck its energy. Dawn and Brock remember Gardenia's last strategy with Leech Seed. Ash knows that he will lose the battle if he can't stop Gardenia's Turtwig. He tells Turtwig to use Synthesis. Gardenia's Turtwig uses Leaf Storm. Ash's Turtwig jumps into the air, dodging the attack. Ash's Turtwig then begins to heal itself courtesy from the sun. Now that Turtwig is fully healed, it uses Razor Leaf. Gardenia's Turtwig gets hit by the attack, but it manages to get back up. Both Turtwig then collide into each other with a Tackle attack. Both Pokémon are exhausted. However, Gardenia's Turtwig falls down first, unable to fight. Ash's Turtwig is the winner.

Ash and co. are glad that Gardenia's Turtwig loss, however Brock states that the Leech Seed is still in effect, and it might knock Turtwig out. Meanwhile, the man has treated Team Rocket to some noodles at a restaurant. Even the the man has taken the treasure with him, Team Rocket is happy because of the noodles. Gardenia's last Pokémon is Roserade. Ash wants to end the battle quickly. He orders Turtwig to charge towards Roserade. Gardenia calls out for the Grass Knot attack. A vine appears and trips Turtwig. Then Roserade uses Weather Ball. Because it is Sunny outside, the Weather Ball is turned into a fire attack. The fire causes Turtwig to faint.

Brock explains that Weather Ball turns into a fire type attack because of the sun. Ash only has one Pokémon left. He sends out Aipom. Aipom uses Double Team. Roserade uses another Grass Knot attack. More vines appear out of the ground. The Aipom copies all get caught in the vines, but the real Aipom dodges them and hits Roserade with its Focus Punch. Then Roserade uses Magical Leaf. Ash orders Aipom to use the trees to dodge the attack. Aipom jumps from tree to tree in order to dodge the leaves. Suddenly, Roserade grabs Aipom and throws Aipom to the ground. When Aipom is on the ground Roserade uses Flash. The bright light blinds Aipom. Ash tells Aipom to use Focus Punch. Aipom uses the attack, but because Aipom is blinded by the light, its attacks miss. Roserade then hits Aipom with its Magical Leaf. Aipom begins to punch in mid-air because it cannot see anything. Ash tells Aipom to calm down. He then tells Aipom to use its ears instead of its eyes to sense the attacks. Aipom takes Ash's advice. Roserade fires one last Weather Ball at Aipom. Aipom uses its ears to sense the attack. When Aipom feels the Weather Ball coming in close, it uses Focus Punch to hit the attack right back at Roserade. Roserade is hit by its own attack.

The battle still isn't over. Roserade is able to get back up. It uses Magical Leaf. Aipom regains its sight again, and it counters with Swift. The Swift overrides the Magical Leaf, and the stars all surround Roserade. Gardenia wonders what Ash is trying to do. Aipom uses another Focus Punch on the stars. The stars all bounce onto Roserade. Then, with one more Focus Punch from Aipom, Roserade is sent backwards and faints. Ash is the winner! Ash is presented with the Forest Badge from Gardenia. Now that Ash has the Forest Badge in his hands, him and his friends continues their journey through Sinnoh.