The Cerulean Gym is the setting for old and new friends, battling old and new skills!

Ash and Pikachu run into Litten again, but this time something's very wrong with its friend the old Stoutland. Ash carries Stoutland to the Pokémon Center, where Ash, Pikachu, and Rotom-Dex learn that Stoutland is dying. Litten and Stoutland escape from the Pokémon Center and return to the riverside, where Stoutland passes away in the night. After realizing what has happened, Litten is heart-broken and refuses to be comforted by anyone. After Litten finally comes to terms with the loss of its friend, Ash asks Litten to join him. Litten decides to test him by battling against Pikachu. When the battle ends in a draw, Litten chooses to become one of Ash's Pokémon. Team Rocket's Meowth, who for reasons of his own has been secretly watching everything, seems pleased by the outcome.

A celebratory Pokémon School class trip turns out to be a reunion no one will ever forget!

The time for Ash's grand trial with Olivia is finally here, and it's no ordinary battle!

As if Ash's victory at his grand trial wasn't monumental enough, an unexpected transformation makes a memorable field trip even more momentous!

The Melemele Island grand trial is imminent, and Ash must square off against the power and wisdom of Kahuna Hala!

A trainer named Gladion, dressed in black, battling with a powerful fiery-eyed Lycanroc and wearing a Z-ring, has appeared on Melemele Island. After seeing them in action, Ash naturally wants to battle Gladion; however, he's totally shocked when Lillie appears and calls Gladion her brother. Gladion seems cold towards Lillie and at first refuses Ash's challenge, but then learns that Ash got his Z-ring from Tapu Koko and had actually battled the Island Guardian. That night, Gladion's Umbreon delivers a note to Ash agreeing to battle. It's Ash's Rockruff versus Gladion's Lycanroc! However, Team Rocket, who saw Gladion defeat the Team Skull grunts earlier, can't resist getting involved. Ash and Gladion must work together to rescue Pikachu and Lycanroc.

Students and Pokémon take a camping trip together. After they wake up feeling mysteriously drained, they realize there's something in the forest.

Ash and his friends switch Pokémon for two days for a class assignment. Ash takes Snowy to his house while Pikachu goes home with Lillie.

Lillie's egg hatches into an Alolan Vulpix, which she had named "Snowy" in the previous episode, and their principal's egg into a normal Vulpix. The fire-type Vulpix starts playing with Pikachu, Togedemaru, Popplio and the others, while Snowy (an ice-type) ignores the others. Finally, it decides to accept Lillie as its trainer and gets caught in Lillie's Pokéball by itself. Lillie decides to spend some time alone with her newfound partner and takes a walk with Snowy. Team Rocket starts following them and soon corners Lillie and Snowy. Though Lillie tries to put up a fight when Snowy uses Powder Snow, Team Rocket dominates her in battle. She and Snowy are saved by Ash and Mallow. Lillie finally learns to touch a Pokémon for the first time, even though this is exclusively for Snowy at this moment.

Ash and Professor Kukui notice that the Rockruff that lives with Professor Kukui is disappearing at night and returning the next morning badly injured. Following it, they find out that Rockruff is participating in a secret Pokémon training ground. Ash decides to help Rockruff train. Rockruff learns to use Rock Throw. After Rockruff defeats a Magmar that previously defeated it, Professor Kukui decides to leave Rockruff in Ash's care and Ash catches Rockruff.

Ash needs to begin training for a possible rematch against Tapu Koko. Sophocles helps out with scientific methods that yields surprising results. Naturally, this arouses Tapu Koko's interest. Tapu Koko challenges Ash and Pikachu with the whole Pokémon school looking on. Are Ash and Pikachu strong enough with the Electrium Z-Crystal power to withstand the Island Guardian's powerful attacks?

The Akala Island Kahuna, Olivia, comes to the Pokémon School. Ash and the rest of the class head to Akala for a practical class under her supervision.

Ash is after his first Pokémon in the Alola region, and the adventure that ensues is typical Ash!

While training on a beach, Lana's Popplio and Ash's Rowlet are caught inside one of Popplio's balloons, which is blown away by a strong wind. Rowlet bursts the balloon open, and they both crash into Team Rocket's secret base. Meowth and Mareanie chase after them, but they are rescued by Litten. While Ash, Lana, and Mallow search for the missing pair, Litten takes them to where it has been staying with the old Stoutland. Stoutland asks Litten to help them find their trainers; however, Team Rocket is also hunting them. Who will find Litten and the lost Pokémon pair first?

On the advice of a local shopkeeper, Ash and Pikachi (partly to escape being dragged along on the girls' shopping spree) kayak to nearby Treasure Island, where there are lots of wild Pokémon. After watching a group of Crabrawler, following an Cutiefly to a meadow full of friendly bug Pokémon and having fun with a group of Alolan Exeggutor, they are overrun by a school of Wimpod who try to steal their snacks. Preparing to return home, they find a Wimpod trapped inside a blocked cave. With the help of one of the Exeggutor from earlier, they manage to reach and free Wimpod, who thanks Ash before returning to its school. Ash and Pikachu see another Island Guardian, Tapu Lele, who heals Ash's bruised hands.

When the Pokémon School announces a special Visitors Day, Ash's mother and Mr. Mime come for a visit. Delia charms everyone, including all of Ash's Alolan Pokémon. Meanwhile, Ash faces one of his toughest challenges ever... giving a report in front of his classmates, the school visitors and now his own mother! When the Team Skull grunts crash the festivities on Tauros and start causing mayhem, Delia insists on standing up to them. Can Ash and his Pokémon save the day?

The Wela Fire Festival is just starting to heat up, but someone seems determined to put it out!

When Mimikyu faces a fashion problem, Jessie sees a bonding opportunity!

A feisty Litten is determined to steal food from others, and Ash and Pikachu are determined to find out why!

Lillie has a Pokémon Egg to care for until it hatches, but will fear get in her way?

Professor Kukui takes Ash and the other students for a special lesson at the beach, where they come across a bunch of Mareanie. One Mareanie causes trouble for Ash and his Pokémon when it decides to help Team Rocket (and especially James), who are under pressure from their boss to catch new Pokémon in the Alola region.

With no class today, Ash and Lana go fishing, but they may end up catching more than they bargained for since the lagoon they're fishing in may contain a water-type Totem Pokémon. If there is, then Lana is determined to battle it. Meanwhile, Kiawe takes the rest of the gang to visit his family's dairy farm, and Team Rocket doesn't seem to be having much luck with their own fishing.

Our heroes are embarking on a mission filled with good taste...and a surprising finish!

Three of our heroes are teaming up for the annual Charjabug race, an electrifying event with shocking results!