Ash is back on Melemele Island, watching a fireworks display with his Pokémon School classmates. Toward the end of the show, a strange creature starts creating even more fireworks ... by making its own head explode! The next day, Lusamine summons the Ultra Guardians to deal with this Ultra Beast! When our heroes go after it, they discover a second Ultra Beast, and the two creatures face off, flinging fireworks and sparks around so no one can get close. At Ash’s suggestion, the Ultra Guardians stage their own fireworks show, combining their Pokémon’s moves into a gorgeous display that distracts the Ultra Beasts long enough to catch them!

On their way to the ferry back to Melemele Island, our heroes take a shortcut through a cave. They find an area filled with luminescent moss, and Kiawe’s overexcited Marowak starts a commotion that separates everyone into groups. While the others try to find their way out, Lillie, Sophocles, and Mallow discover a group of Alolan Sandshrew in training. The Sandshrew are threatened by a Tyranitar, but Lillie intervenes. She challenges Tyranitar to a Double Battle—and wins with the help of Snowy and the Sandshrew Boss! To show their gratitude, the Sandshrew present Lillie with her very own Icium Z!

Professors Kukui and Burnet have a hard time getting up in the morning, and when Ash gets to school, he discovers that the adults in his friends’ lives are in the same boat! The Aether Foundation team has a theory, but they’re exhausted too, so Ash takes charge of the Ultra Guardians (now including Gladion) to investigate. The culprit seems to be something on the other side of an Ultra Wormhole, draining all the energy from the Ultra Auras. Our heroes track down the wormhole, and they’re excited to see the Legendary Pokémon Lunala emerge—but a mysterious and frightening creature is right on its tail!

The Ultra Guardians spring into action to protect Lunala from the mysterious creature who has chased it through the Ultra Wormhole! UB Black (as Lusamine later calls it) drains the power from Lunala’s Ultra Aura, then fastens itself onto the Legendary Pokémon to absorb it! Our heroes manage to fight it off with the help of Solgaleo, but the creature turns a similar attack on Solgaleo, absorbing it and escaping through an Ultra Wormhole. As Lunala recovers its strength, the Ultra Guardians promise to do everything they can to rescue Solgaleo—and the kahunas prepare for a festival celebrating a solar eclipse!

Our heroes have made it through the Ultra Wormhole, but when they find the captured Lusamine, they’re shocked to find she wants nothing to do with them! With an Ultra Beast controlling her mind, it’s up to Lillie, Ash, and friends to rescue her. Their Pokémon spring into action—but so do Lusamine’s Pokémon, who are also under the Ultra Beast’s control. Lillie gathers her courage and reaches out to Clefable, recounting the fun they had together in years past. Her reassuring persistence pays off, and Clefable breaks free of the Ultra Beast’s control. Meanwhile, riding on Solgaleo’s back, Ash presses on to find Lusamine—and the Ultra Beast.

Our heroes are battling hard against a group of mind-controlled Pokémon, and Lusamine is still resisting rescue. When Gladion realizes their attacks won’t stop until the Ultra Beast is defeated, Ash suggests the two of them use Z-Moves. Instead, Gladion and his Pokémon provide a distraction while Ash and Pikachu use a powerful new Z-Move: 10,000,000 Volt Thunderbolt! This finally defeats the Ultra Beast, and after Lillie pleads with her mother to wake up, Lusamine is finally herself again. Returning through the Ultra Wormhole, our heroes and Lusamine are reunited with Professor Kukui and Professor Burnet, and Lusamine gratefully gives credit to our heroes for saving her.

After the mysterious creature known as UB Black absorbs Solgaleo and retreats into an Ultra Wormhole. Ash and his friends give chase and find themselves in Poipole’s original home. There, they meet a giant Pokémon named Naganadel, who tells our heroes of the threat to its world—and how UB Black may be the only hope of saving it!

Lillie can touch Pokémon again! While our heroes celebrate, a disgraced Faba is determined to prove himself to Lusamine by summoning an Ultra Beast—the same one that threatened Lillie years before. He kidnaps Nebby and convinces it to teleport him into his research lab at Aether Paradise. Ash, Gladion, Lillie, and Lusamine go after Faba, arriving just as a panicked Nebby transforms into a chrysalis and the Ultra Wormhole begins to open! The Ultra Beast known as UB-01 Symbiont emerges and attacks Lillie—but Lusamine throws herself in front of her daughter, and the Ultra Beast engulfs her instead and takes her back through the wormhole!

The mysterious Masked Royal and his partner Incineroar star in the Battle Royal, an Alolan tradition in which four Pokémon battle until the last one standing is the winner. Ash, watching on TV, can’t wait to get in on the action—and the next day, he gets his chance! At the Battle Royal Dome, Ash’s Litten charges right into the ring, determined to take on the impressive Incineroar. The Masked Royal accepts Litten’s challenge and invites Sophocles and Kiawe to round out the four. He defeats them all, but Litten is fired up—and during an unexpected rematch the next day, it evolves into Torracat!

Ash and his Pokémon School friends visit Hokulani Observatory to view a meteor shower. But these aren’t normal meteors. They’re the space-dwelling Pokémon Minior, crashing to the ground in vast numbers! Guided by Sophocles’s cousin, Molayne, our heroes settle in for a night of making wishes on falling “stars”. When Minior land, they typically burst out of their protective rock shells, filling the evening sky with color and light. This amazing display creates a festive mood, but the celebration seems to bring back sad memories for Sophocles...

After accidentally seeing Gladion and coming face-to-face with Silvally, Lillie is once again unable to touch Pokémon—but she’s determined to change that! With Nebby’s help, she embarks on a journey to recall the memories behind her fear. But Faba wants none of it, having been responsible for Silvally’s creation in the first place. Vowing to make sure Lillie never remembers her past, Faba captures her, and she’s again filled with fear. But Silvally rescues Lillie, and when she remembers that it was the one who saved her in the past, her fear of touching Pokémon finally vanishes!

Sophocles is out camping with his parents and Pokémon at Bamboo Hill when he finds a strange metallic object buried in the ground. Remembering a folktale, he believes it to be the legendary spaceship Celestial Starship. The next day, after he tells his classmates about it, they go there and see it for themselves. After an unsuccessful attempt to dig it up, they return to school, where they are contacted by Lusamine about an Ultra Beast having been detected. Sophocles is surprised to discover that the Pokémon he discovered is a Celesteela, and they determine to return it home. Attempts to catch it in a Beast Ball prove unsuccessful as it is firmly rooted down. Team Rocket attempts to catch Celesteela as the Ultra Guardians try to protect it, and Team Rocket is almost incinerated as Celesteela begins to launch itself. After the Ultra Guardians create a safe launch area, they watch Celesteela fly home.

The Ultra Guardians are beside themselves with excitement, as Lusamine has booked them a day at the Pokémon Paradise Resort—and the hardworking Ride Pokémon are tagging along, too! Everyone enjoys the spa’s relaxing amenities, but Team Rocket shows up in disguise with other plans: stealing all the Pokémon they can! Fortunately, the Ride Pokémon have none of it, and they make sure to dash the troublemakers’ ambitions. Our heroes finish their spa day in total luxury, while Team Rocket ends up stuck in the mud with Bewear...

After dreaming that he made a promise to the Legendary Pokémon Solgaleo and Lunala, Ash has a hard time waking up. On his way to school, he’s sidetracked by Tapu Koko, who guides him to a strange little Pokémon that looks like a cloud of stars. Lillie nicknames it Nebby, and Ash remembers his dream: he promised to take care of it! This attracts the attention of Lillie’s mother, Lusamine, the head of the Aether Foundation. She and her colleagues come to meet Nebby and offer to take care of (and research) this unknown Pokémon. But Ash is resolute in his promise, so Nebby’s identity is a mystery for now!

When Ash gives Lycanroc a bath, an accidental splash of dirty water unleashes Lycanroc’s surprisingly red-hot temper! Then, when our hero wonders aloud what Gladion is up to, Nebby teleports Ash and Pikachu to him. They meet Silvally, a Pokémon created to defeat Ultra Beasts—and Gladion is convinced that Nebby is one! Suspicious, Gladion wants to know what Ash is up to, and our hero suggests a battle so he can find out! Ash’s Dusk Form Lycanroc faces off against Gladion’s Silvally. Lycanroc battles magnificently, but another temper tantrum betrays its inexperience, and Silvally wins. But Gladion decides Ash is trustworthy, and their friendship starts to grow…

Our heroes are all gathered at the Altar of the Sunne, along with all four of Alola’s Island Guardians. Lillie and Gladion ask the Island Guardians for help to rescue their mother, Lusamine, who has been taken through an Ultra Wormhole by a mysterious Ultra Beast. After Tapu Koko and the others perform a ritual, little Nebby evolves into the mighty Solgaleo—one of the Legendary Pokémon of Alola! At Solgaleo’s invitation, the Pokémon School students climb onto its back. With the help of a new Z-Move, Solgaleo opens an Ultra Wormhole and carries them through, off to rescue Lusamine from the Ultra Beast!

Following their journey through the Ultra Wormhole, our heroes return to the Pokémon School, where Lillie thanks everyone for their help saving her mother. Later, during a walk on the beach, Professor Kukui asks Professor Burnet to marry him! They aren’t planning a wedding ceremony, but our heroes have other ideas...a surprise ceremony awaits! Then, Lusamine asks the Pokémon School class to join the Ultra Guardians—a group that protects Alola from Ultra Beasts. And just after the bouquet toss, Solgaleo appears! Ash gets his wish and thanks the Legendary Pokémon for all its help, and he looks forward to seeing it again someday.

Our heroes are learning all about Pokémon Ping-Pong, with Pokémon School graduate Ilima showing them the ins and outs of the game! Ilima plans to compete in an upcoming Pokémon Ping-Pong tournament, where he hopes to settle an old score and defeat Ikari, the winner in previous years. But while Ilima believes that consideration for his Pokémon partner is key to success, Ikari takes a more aggressive strategy. After Ikari berates his partner Mienshao during the heat of the tournament’s final game, the two lose coordination, and Ilima and his partner Smeargle emerge victorious!

Thanks to Acerola’s help, Ash arrives at the Ruins of Abundance, home of the Ula’ula Island Guardian Tapu Bulu. Ash wants to train with Tapu Bulu to prepare for his rematch against the Island Kahuna Nanu, and after our hero demonstrates his friendship with his Pokémon, Tapu Bulu springs into action! Showing immense power, the Island Guardian engages Ash and Lycanroc in battle. Lycanroc learns how to use Stone Edge! As the bond between Ash and Lycanroc grows, Tapu Bulu returns to its nap, satisfied that the training session was a success!

With his pre-trial successfully behind him, Ash is finally ready to take the Ula’ula Island grand trial against Kahuna Nanu. Our hero is taken aback when Nanu reveals the terms of the challenge, though—Ash must defeat three of Nanu’s Pokémon with only one of his own! Ash decides that Lycanroc is up to the task, but the temperamental Pokémon might have trouble keeping its anger under control...especially when Nanu unleashes a barrage of taunts questioning Ash and Lycanroc’s teamwork.

The Pokémon School has a visiting teacher: Faba! When he shows off his invention that can reduce the size of objects for easy storage, it malfunctions, and Ash, Lillie, and Sophocles are shrunk into tiny heroes! Faba recruits Rotom Dex to help him repair the machine, and meanwhile, our heroes are thrown into a world where everything is gigantic. They eventually reunite with Pikachu, who sneezes on them—causing them to return to normal size. But just when Faba thinks he’s fixed his invention, it misfires again…and the result is a towering Togedemaru!

Our heroes are in shock after Lusamine’s disappearance through an Ultra Wormhole, and they want to help get her back. But Gladion insists it’s a family matter, and he and Lillie set out on their own rescue mission. The Pokémon School class still wants to help, though, so Kahuna Hala directs them to the Altar of the Sunne on Poni Island. Meanwhile, nearing the altar, Gladion and Lillie encounter a Totem Kommo-o! With Snowy and Silvally, they defeat the Dragon-type Pokémon. Then, when the siblings rejoin the rest of our heroes, Ash again tries to convince Gladion to let everyone help. And when Lillie agrees, Gladion finally understands…

Lusamine gives our heroes their first assignment as members of the Ultra Guardians: catch an Ultra Beast named Buzzwole, who emerged from an Ultra Wormhole on Melemele Island. Equipped with the latest technology, the Ultra Guardians locate the Pokémon, whose aggressive behavior seems to reflect its anxiety about being in a strange world. Ash and Kiawe notice Buzzwole has a habit of striking heroic poses—so they join right in! With Buzzwole’s guard down, Ash catches it in a Beast Ball, and it’s soon returned to its own world through the reopened Ultra Wormhole. Though our heroes will miss Buzzwole, their first mission as Ultra Guardians is a rousing success!

One day during class at the school, an unrecognizable creature comes to Ash and the others. When they notice it, the creature disappears, but for some reason they can no longer see Pikachu around either. It appears Pikachu was taken away by the earlier creature. An agitated Ash starts searching for Pikachu, but suddenly runs into Team Rocket.

The annual Alola Bread Festival is coming up, and Mallow’s brother Ulu has unexpectedly returned home to enter! When Nina from the pancake restaurant stops by to wish Ulu good luck, he vows to win for her sake. But all his sweet Grepa Berries disappear, so our heroes jump in to help save his entry. Mallow suggests making jelly from sour Grepa Berries, sweetening it, and spreading it on Ulu’s bread. And it works! Ulu’s bread wins first prize…but when he discovers Nina’s already engaged to someone else, he suddenly takes off again on his cooking journey!