Team Rocket's failed attempt to catch Pikachu has left the little yellow Pokémon dangerously ill. Littleroot Town has no Pokémon Center so Ash turns to Professor Birch for help. Professor Birch thinks that Pikachu can be cured—but first they'll have to catch it. Delirious with fever, Pikachu has run off into the forest. Meanwhile, a girl named May is also going to see Professor Birch in order to receive her first Pokémon. She arrives just in time to save the professor from a pack of mad Poochyena. Before he can explain why he's running around in woods, Professor Birch runs off in search of the missing Pikachu. Time is running out and Pikachu is in danger of exploding. In a twisted turn of events, Team Rocket's latest Pikachu-catching contraption ends up saving the day.

Now that Pikachu is feeling better, Ash is ready to head to Oldale Town to sign up for the Hoenn League. May has offered to show Ash the way in exchange for his company to Oldale Town—which is only fair, seeing as Pikachu destroyed May's bike when it was sick! In Oldale Town, May visits her first Pokémon Center and is amazed with all of its services, and by the ancient ruins next door. Things quickly turn sour when Team Magma, a mysterious band of criminals, shut down the electricity at the Pokémon Center and kidnap Professor Alden in order to invade the ruins. With no electricity, all of the Pokémon are in danger—including May's Torchic. It's up to Ash and May to save the day—and in doing so they uncover mysterious, ancient Pokémon.

Ash and May have made it all the way to Petalburg City—the first city with a gym. Ash is very excited to take on the gym leader. May seems a little uneasy—perhaps it's because she hasn't yet told Ash that her father, Norman, is the gym leader in Petalburg! When Ash first gets to the gym, he meets May's little brother, Max, who is pretending to be the gym leader. Max knows a lot about Pokémon and can't wait until he's old enough to become a trainer. Once Ash finally meets Norman, he learns that he will need three Pokémon in order to battle at the gym. He only has Pikachu with him. When Norman agrees to an unofficial battle, Ash encounters his first Vigoroth. Ash realizes that he will have to train hard in order to win a badge in Petalburg City. After a quick scuffle with Team Rocket, Ash and May are ready to hit the road again. Max has decided to tag along, too!

Ash, May and May's little brother Max are now en route to Rustboro City—and they're hungry! No one remembered to pack lunch. As they fight over one remaining cookie, Ash remembers how nice it was to have Brock cooking for him and Misty. He's quickly brought back to reality when a Taillow takes off with the cookie. The gang follows Taillow to a grove filled with apple trees. Ash and May eagerly shake the trees, hoping to make the apples drop to the ground. Instead of apples, Ash and May shake loose an angry flock of territorial Taillow. There's too many for Ash, Max, and May to handle alone. Out of nowhere, Brock appears and saves the day with his Forretress—and his incredible soup! They manage to defeat and feed all of the Taillow except the one who took the cookie. Taillow are naturally resilient, but this particular one is especially tough. Ash can't seem to defeat it, so instead he decides to catch it

With his old friend Brock back travelling with him, Ash finds things are returning to normal with all the successful battles. However Ash & Co. see a Zigzagoon and a guy chasing it to capture it. it turns out his name is Nicolai and he is training Pokémon to be able to beat Norman. May & Max dont like this so May challenges him to a battle. Will she win her first battle?

Our heroes are headed for Rustboro City, where Ash hopes to have his first real gym battle in Hoenn. Team Rocket is making their way along the same path when they stumble upon a cage full of Ekans. Jessie is delighted that their work has been done for them and orders Arbok to attack. Arbok can't manage to attack the helpless Ekans, however, because it remembers when it used to be an Ekans. Jessie is sympathetic. James soon makes a similar concession when they find a cage of Koffing that Wheezing will not hurt. The cages belong to a poacher named Rico who uses his Fearrow and Pupitar to chase off Team Rocket. Team Rocket returns to the scene, now hoping to free the Ekans and Koffing. Things turn dangerous when Rico's Pupitar evolves into a Tyrannitar, and Team Rocket is forced to make the ultimate sacrifice for the Pokémon that they love.

Deep in the woods, Ash spies a Treecko. He's wanted to catch a Treecko since he first saw one at Professor Birch's laboratory. He follows the Treecko to an enormous tree that seems to be dying. There, Ash's Treecko has an argument with all of the other Treecko. It seems that Ash's Treecko is very attached to the tree and wants to stay with it, while the rest of the clan wants to move on to a new tree. Ash watches as the lone Treecko struggles to save the tree. He and Pikachu feel badly for the Treecko and try to help. In the end, however, the tree dies and falls. Now that its home is gone, Treecko is ready to make a new home with Ash. He and Pikachu battle, and Ash catches his Treecko!

Ash's newly caught Treecko may be a bit standoff-ish, but the little green Pokémon is quite a fighter. When Team Rocket sees Treecko knocked down and hurt by a Seviper, they decide that they must have that Seviper. Jessie is very impressed with its "sneaky, snakey ways." Meanwhile, Treecko escapes from the Pokémon Center where Ash brought it to recover. When the gang finds Treecko, it is practicing its attack moves. Again and again, Treecko jumps from the top of a waterfall and tries to break a rock at the bottom with its tail. Ash is very impressed with the rigor of its training. All of Treecko's hard work appears to have paid off—when Team Rocket attacks and catches Pikachu with the help of their new Seviper, Treecko is able to save the day.

On the Way to the next gym, Ash & Co. discover a Shroomish, and it turns out none have come to the town for Ages. They appear to be hiding in a Mansion since humans are constantly cruel to them. However Team Rocket want to steal them. Will they?

While Ash and Co. continue their journey, they meet Anthony and his Pelipper, which is said to be the world's most powerful Pokémon. The reason is that his Pelipper knows Fire, Grass and Electric-type moves instead of only Water and Flying-type moves. How is Ash going to defeat Pelipper, and what are Anthony's Bellsprout, Magby, and Magnemite doing in Pelipper's mouth?

Whilst Ash and his friends are relaxing in a forest, three Mightyena and a Poochyena ambush them. While they are trying to protect themselves from the Pokémon, they are rescued by the Ranger of the Forest, Katrina. She wards off the wild Pokémon and takes the group to her house. Meanwhile, Team Rocket overhears that the forest is full of rare Pokémon. Back at Katrina's house, Max creates a bond with her Poochyena and tries to make it evolve, with minimal success. Is Poochyena going to evolve and is Max going to understand the importance of evolution?

Ash and co. are having a good time swimming at a lake when a crew of Lotad appeared and threw them out of the pool. Later, they figure out that these Lotad are taken care of three sisters, Nicole, Natalie and Rita, which are holding a flower shop with many kinds of Berries. During this time, Natalie develops a crush on Brock, which leads her to do something risky. At the same time, Brock helps a Lotad that doesn't know how to use Water Gun properly. How will this friendship go and what will happen with Natalie's crush?

Rustboro City is on the horizon, but they're not there yet. Ash, Brock, Max and May have just arrived at a Contest Hall. Janet and Chaz, two experienced Pokémon Coordinators, teach the gang all about Contests. Pokémon Contests are different from battles in that it's not the strength of the attack that matters, but the beauty of its execution. Winners get ribbons instead of badges. The gang decides that they want to try entering today's contest, but they're too late. All is not lost, however, because Chaz offers to teach Pikachu the Iron Tail attack. And Janet lets May assist her with during the contest. During the contest, Chaz and Janet both perform really well and make it to the final round. In the end, Janet's Beautifly steals the show! May is really impressed and she's determined to one day enter a contest herself.

As the gang continues to make their way towards Rustboro City, May spots a Wurmple that she's dying to catch—but she's not the only one with her eye on the cute little bug Pokémon. Jessie wants it, too. May ventures off on her own to catch her Wurmple, but Team Rocket follows and gives her trouble. Luckily, she gets some help from a trainer named Franklin. Meanwhile, Ash and Pikachu are practicing Pikachu's Iron Tail attack. A trainer named Franklin sees them practicing and challenges them to a battle. Franklin teaches Ash about double battles, which are common in the Hoenn region. With help from her new friend Franklin, May catches the Wurmple she wanted. When she and Franklin go to meet up with the gang, everyone is really surprised. The Franklins are actually identical twins—Forrest and Forrester Franklin! All is not lost for Team Rocket, however. Jessie manages to snag a Wurmple of her own before Team Rocket blasts off at the end of the episode.

Ash and friends arrive at Rustboro City where he gets silly with souvenirs. Max then notices a Poliwag hiding and soon the gang meets Roxanne, teacher of the Pokémon Training School and Rustboro Gym Leader. Will Ash get his first Gym Battle in Hoenn, and what of May? And how can Max fair against the school bully?

Pikachu is getting pretty good at its Iron Tail attack and that's a good thing. Ash is finally about to take on Roxanne, the leader of the Rustboro City Gym. He's going to need all the help he can get to take down her Geodude. May, on the other hand, isn't really looking forward to the battle. In fact, she announces that she's not going to be a trainer anymore. She wants to become a Pokémon Coordinator and compete in contests instead. When the battle begins, it doesn't look like Ash has much of a chance. Roxanne's Geodude knocks out Treecko pretty quickly. It's all up to Pikachu. Electric attacks aren't going to help much against a strong Rock Type—but Ash is very clever and Pikachu not only brings down Geodude, but it wipes out Nosepass with its newly perfected Iron Tail Attack. Ash defeats Roxanne and receives his Stone Badge.

After winning the Stone Badge from Roxanne, Ash and co. head out to the next gym, located on Dewford Island. However, Max spills a drink on his PokéNav and rather than suffer her wrath, Max tries to find a quick solution. He sees an old man demonstrating new inventions but before he can go further, a younger man picks him up in a limo. Who is this old man, and can he help Max fix the PokéNav before May finds out it's broken?

May may be the new Misty but she is not as smart as she was. And she proves this when she, Ash, Brock and Max head to a pasta restaurant that May read up on the internet. The thing was May forgot to check the date and found that the place was closed. The date was exactly the same day, exactly the same month, ten years ago. Things go from bad to worse when they find the pier on the other side of town. May tries to find help and finds a kind sailor by the name of Mr. Briney. But when she returned with her friends, his personality changed for the worse. Could May have goofed up again? Or is someone else pulling Mr. Briney's strings?

After the incident with the Team Aqua agent and with Peeko safely returned to Mr. Briney, Ash and co set sail for Dewford Island. All is not calm on the way there however as a school of Sharpedo suddenly attack Mr. Briney's boat. Not to mention tear up a part of May's new swimsuit. Now how will Ash and co. get to Dewford with all the Sharpedo in the way? Is this going to be like "Jaws" all over again?

After a night at the Pokémon center, Ash is stoked to have another Gym Battle. He meets the Gym Leader Brawly, who would rather surf than battle, which infuriates Ash. Could there be more to this Gym Leader than meets the eye? And does May even have a shred of decency?

After being beaten by Brawly, Ash decides to stay at Dewford Island and do some serious training of one thing he lacks: patience. He does this by practicing the fine art of Fishing. He, along with May, Max and Brock, accidentally hook Team Rocket's Magikarp submarine and after a fierce battle, May notices something different about her Wurmple: it is actually Jessie's. Can the heroes find May's Wurmple before Team Rocket figures it out?

While exploring Dewford Island, Ash and friends notice a large cave and Max states that it's Granite Cave. They all enter and soon they fall into a pit trap courtesy of Team Rocket. Unfortunately, they fall in as well and the two groups are mixed and separated. This time around, there are three groups: Males being Ash, Brock and James. Females being May and Jessie and the rest being Max, Pikachu and Meowth. Can these groups be brought back to order and who is in Granite Cave along with our heroes and villains?

A mysterious Pokémon is terrorizing Dewford Town's beach. Ash and friends set many traps for the terror and discover its identity, Corphish. Will Ash and his friends be able to capture the feisty Water-type Pokémon, or will it set them out to dry?

With a new Pokémon in tow, Ash continues his training to prepare for his rematch with Brawly. However, Corphish is still a ruffian as it introduced itself by whacking all the other Pokémon on the head. Can it ever be more social with other Pokémon, and why is Jessie's Silcoon purple right after it evolved?

Get ready for a new episode of May's Expedition as she, Ash, Max and Brock stumble upon a swamp. There they find a swamp full on Mudkip and their caretaker, an elderly man named Old Man Swamp (or Mr. Swampy) who has the same whiskers as a Mudkip's fins. He explains that he gets Mudkip eggs from the Hoenn League and when they hatch they wait until they're old enough to give to Professor Birch. But Team Rocket also has plans for the Mudkip. What evil will they have in store for them, and will Brock get a new friend?