Before Ash's gym battle, Ash is trying to perfect Pikachu's Iron Tail. They have just finished splitting a boulder into two pieces. Brock, May, and Max are eating lunch and watching Ash train Pikachu. They are impressed at the amount of work Ash put in with training Pikachu. Ash tells Pikachu to use Iron Tail on another rock. Unfortunately, the attack fails and Ash sighs.

Ash and Pikachu stop their training for a lunch break. Brock tells Ash that even if Iron Tail did work, it would take much more than that to defeat Roxanne's Geodude. Max asks May what her strategy is for her gym match. May tells everyone that she won't be battling gym leaders. She instead wants to become a Pokémon coordinator just like Janet. Ash and Brock are happy that May has found something that she wants to do. Max is disappointed that May is choosing to be a coordinator instead of a trainer.

James is looking in a Pokémon book. He is surprised to see that Roxanne is the gym leader. They all want to steal Roxanne's Pokémon. James, however thinks they should come up with a new plan because all of their previous plans have failed before. He says that digging up a tunnel will work.

Ash and co. have entered the gym. They see an awesome battlefield in the center of the gym. A bunch of people are preparing the battlefield for Ash and May. Roxanne shows up. She is glad that Ash and May are beginning their journies at Rustboro City. Before the battles can start, May tells Roxanne that she wants to become a Pokémon coordinator rather than a trainer. Roxanne understands and she wishes May the best of luck. Roxanne decides to make a video of the battle with Ash because it helps students learn better. Max is very excited because it is the first gym battle he is going to see.

The battle begins. Roxanne sends out Geodude. May looks up Geodude in her Pokédex. May and Max notice that Geodude is a very strong Pokémon. Ash sends out Treecko. Being a Grass type, Treecko has the type advantage over Geodude except Treecko doesn't know any grass attacks. Treecko starts off with Quick Attack, but Geodude just blocks the attack. Roxanne tells Ash that physical attacks won't do much damage on Geodude. Geodude uses Mega Punch on Treecko. Treecko lands in the air. Then it charges down towards Geodude and uses Pound. The force from the attack sends Geodude backwards into a pile of rocks. Roxanne is impressed at Ash's move. However, Geodude has recovered from the attack. It uses Rollout. Treecko dodges the attack, but Geodude flies up near Treecko and strikes it down with Mega Punch. Treecko is knocked out.

Ash's next Pokémon is Pikachu. Roxanne is surprised that Ash would choose an electric Pokémon for the battle, however Ash is confident that he will win. Pikachu starts the battle with a powerful Thunder. The attack flattens the whole battlefield.

Meanwhile, Team Rocket is digging a tunnel underground towards the gym. Jessie and Meowth are tired, but James doesn't want anyone to take a break. Jessie wants to know how James plans to capture the Pokémon. James tells them that they will dig their way to the gym floor, grab Pikachu, and escape underground. He adds in that using expensive equipment always leads to disaster.

May and Max think that Pikachu's Thunder attack was awesome although Pikachu could've lost a lot of energy. Roxanne tells Ash that now that the battlefield is flattened, Geodude can launch more attacks. Geodude uses Rock Throw, but Pikachu dodges all the rocks by using Quick Attack. When Pikachu gets close to Geodude, Geodude hits Pikachu with Mega Punch. Then Geodude uses Rollout, however it gets stuck in the ground. Pikachu then uses Quick Attack to get close to Geodude. Then with a powerful Thunder attack, Geodude is knocked out. Roxanne is impressed at Ash's battle skills.

Roxanne's next Pokémon is Nosepass. Ash looks up Nosepass in his Pokédex. Pikachu is exhausted from its last battle. Hopefully they can get through the next battle. Pikachu uses Iron Tail on Nosepass. The attack works, and Nosepass slides backwards. Nosepass charges for Pikachu, but Pikachu dodges and uses Iron Tail again. This time, however, the attack doesn't work. Nosepass uses Rock Tomb which seals Pikachu in a cave of rocks. Pikachu blows the rocks away with Thunder. However, this causes Pikachu to lose even more energy. Then Nosepass uses Sandstorm. A large sandstorm is whipped up making it harder to see. However, Nosepass can track down Pikachu because its nose can act like a compass.

When the sand disappears, Nosepass has Pikachu pinned down the the ground. Nosepass lifts its foot up. Before it can slam it down, Pikachu moves out of the way. Nosepass then uses a series of Rock Tombs. Pikachu dodges them all and circles Nosepass. Their strategy is to try and confuse Nosepass. Roxanne tells Nosepass to sense Pikachu's electricity instead of looking for it. Pikachu leaps up and tries another Iron Tail, but the attack fails again because Pikachu doesn't have enough energy. Suddenly, Nosepass jumps up and uses Thunder Wave. Pikachu dodges the attack. James sticks his shovel out on the gym arena. The Thunder Wave hits his shovel, and the electric current blasts them out from the ground and in the sky.

Ash wonders what to do. Pikachu is very weak now, and there aren't many options left. Suddenly, he sees electricity spark on Pikachu's tail. He gets an idea. Pikachu begins to charge towards Nosepass. Nosepass fires a Zap Cannon, and Pikachu absorbs the attack. Then Pikachu hits Nosepass with its own electricity. This causes Nosepass to become paralyzed. Now that Nosepass is paralyzed, Pikachu strikes it with one last Iron Tail and knocks Nosepass out.

Roxanne thanks Ash for a great battle. She and her students have learned a lot from it. Then Roxanne gives Ash his first badge, the Stone Badge. Now Ash and co. focus on getting to the next town.