While Ash and co. are walking to Rustboro City, they decide to stop for a lunch break. Ash, May, and Max gaze at the delicious food that Brock is making. When Brock tastes the food and says that it is ready, everyone sends out their Pokémon to enjoy the break. When Treecko comes out, the other Pokémon stare at it since Treecko is a new member. Ash tells the other Pokémon to say hello to Treecko. The other Pokémon say hello, but Treecko just climbs on a tree and sits on a branch. Ash calls Treecko back for lunch. Treecko takes a twig from the branch and puts it in its mouth. Since Treecko are tree dweller Pokémon Brock thinks that Treecko is just more comfortable sitting on the tree.

Everyone is enjoying Brock's meal. Ash notices that Torchic is running with its food. May tells Ash that Torchic always gets excited when it comes to food. Max states that Pokémon learn their behavior from their trainers. May gives Max a look. Ash calls out for Treecko again. It presents Treecko its lunch, but Treecko doesn't even look at it. Then it notices something moving in the bushes. It is a Seviper. The Seviper eyes May's Torchic. While Torchic is running, Seviper extends its tail out causing Torchic to trip. The apple in Torchic's mouth falls out and rolls into the bushes. Torchic chases after it. It comes face to face with Seviper. Seviper takes the apple and eats it. Seviper gives Torchic a scare. Before Seviper can go after it, a twig falls down near Seviper. Treecko comes and protects Torchic. Torchic screams.

Ash and co. run to the scene. Ash looks up Seviper in his Pokédex. Seviper bounces Torchic on its tail. Ash calls out for Pikachu and Taillow to help Torchic. Brock sends in Forretress. Before the three Pokémon can attack, Seviper uses Haze to fog up the area. No one can see anything. Treecko looks up and sees a tree. It runs up the tree. While Seviper isn't looking Treecko attacks Seviper with its Pound attack. Torchic falls off of Seviper's tail. Treecko catches Torchic and brings it back to May. Angry with Treecko, Seviper hits Treecko with a Poison Tail. Treecko is slammed against a tree. Before Seviper can attack again, Taillow hits Seviper with a Wing Attack. To keep Seviper from moving, Forretress paralyzes Seviper with Spikes. Then a Thunderbolt from Pikachu sends Seviper away.

Unfortunately, the attack from Seviper really did some damage for Treecko. Brock says that he saw a Pokémon Center earlier. Ash picks up Treecko and they all head to the Pokémon Center. Team Rocket has been watching the battle. They want to capture Seviper because of its power. Meanwhile Seviper scares off a trio of Zigzagoon. It swallows the three apples the Zigzagoon were eating. Team Rocket is carefully watching Seviper. Meowth says that he has hidden a trap for Seviper. Seviper sees a basket of fruit. Happy, Seviper crawls towards the basket. Seviper sees the trap that Team Rocket has hidden. It picks up the basket with its tail and crawls away. Team Rocket comes out. They are angry at Seviper for not falling in their trap when all of a sudden they fall in their trap themselves. Team Rocket then throws a net over Seviper. Unfortunately for them, Seviper bites the net releasing itself from the net and crawls away.

Ash and co. have arrived at the Pokémon Center. Treecko is hooked up to some wires and put to rest. Ash hopes that Treecko will be okay. Meanwhile, Team Rocket is eating their lunch. They try to think of a plan to catch Seviper. They all put their hand on the last rice ball. The three of them fight over who gets to eat the last rice ball. Because of their fighting, the rice ball falls in the lake. However, Jessie has secretly stored an extra rice ball in her stash. Before she can eat it, the Seviper reaches out and grabs the rice ball and eats it for itself. Jessie gets angry at Seviper. She sends out Wobbuffet for battle. James reminds Jessie that Wobbuffet is useless unless it is attacked. Jessie returns Wobbuffet and sends in Meowth. With a whip of its tail, Seviper slashes Meowth backwards and into Jessie and James. Another rice ball falls out of Jessie's stash. Jessie runs after the rice ball. The rice ball is about to go into Seviper's mouth, but instead it eats Jessie's hair. This gets Jessie furious. With red glowing eyes, Jessie uses her own attacks on Seviper. She uses Fury Swipes and Mega Kick. Then Jessie throws a Pokéball and captures Seviper.

Nurse Joy reports that Treecko will be fine after a short rest. May asks Nurse Joy if she is the sister of the Nurse Joy in Odale Town. Brock somehow corrects May. Suddenly, Chansey comes in and tells Nurse Joy that Treecko has snuck out of its room. Everyone rushes outside, and they call out for Treecko. Max finds Treecko's bandages. It appears that Treecko ran for the hills. Ash is going to find out why.

Treecko stands on top of a waterfall. Right below the waterfall is a rock. Treecko throws its stick on the ground and jumps off the ledge. Ash and co. continue to search for Treecko. Max points to a waterfall. They see Treecko there. Treecko is hitting the rock over and over with its tail. Brock says that Treecko is training. Since Treecko lost to Seviper it wants to push itself to destroy the rock and finally beat Seviper. Treecko tries over and over to destroy the rock. Finally after several tries Treecko spins in the air and breaks the rock. Ash runs out to congratulate Treecko.

Suddenly, a mechanical arm comes out from the bushes and grabs Pikachu. Team Rocket comes out, and they say their motto. Ash sends out Taillow, and James sends out Cacnea. Cacnea fires a Pin Missile at Taillow, but Taillow dodges the attack. Then Jessie sends out Seviper. Ash and co. are surprised that Team Rocket managed to catch it. Treecko steps up to battle Seviper. Before Treecko can start the battle Ash reminds Treecko that he will be at Treecko's side the whole time. Seviper starts off with a Poison Tail, but Treecko uses Quick Attack to dodge Seviper's attack. Then Treecko strikes Seviper with Pound. Seviper recovers from the attack and uses another Poison Tail. Just before the attack can hit Treecko, Treecko jumps up and uses its same attack like before to destroy the rock. Seviper crashes into Team Rocket. Meowth drops the cage and it opens. Pikachu gets out of the cage and blasts Team Rocket off with a Thunder attack.

Ash congratulates Treecko for beating Team Rocket. Treecko is happy, and it extends its tail out to Ash and Pikachu. They both gently shake Treecko's tail. Ash and co. continue their journey to Rustboro City.