At the Pokémon School, Ash and his classmates are having sports class. Professor Kukui calls for Mallow, and when he blows a whistle, Mallow runs towards a vaulting box and successfully jumps over it. Mallow's friends all congratulate her and Tsareena offers her a high-five. Before Lillie has her turn, she states her theory for getting the best jump, but fails to get over the box. Sophocles is next, but is unsure of himself and simply walks towards the vaulting box. Seeing this, Togedemaru tackles Sophocles, and the boost helps him clear the jump. As Sophocles is in disbelief, his friends congratulate him. Sophocles reacts with slight bashfulness and then thanks Togedemaru. Ash is up next and he asks for two more steps, which raises the vaulting box to eight steps. As he runs up to the springboard, he trips on it and slams face-first into the obstacle. Kukui tells him to be more careful where he steps and calls for Kiawe. Kiawe has another two steps added to the box, raising it to 10. He compares the vaulting box to Wela Volcano and successfully clears the 10 steps. As Kiawe brags, his record is beaten by Lana, who jumps over 12 steps. Lana boasts that she could clear 15, Ash declares that he wants to try for 20, and Kiawe states he will go for 30. Rotom states that they don't have enough steps for that much; Kukui adds that he will prepare some later and tells everyone to just practice jumping in the meantime.
Later that evening, Ash, Kukui, and Professor Burnet walk through Hau'oli City with shopping bags in hand. Kukui and Burnet talk about Ash's earlier declaration, and Rotom calculates that Ash's chance of jumping over 30 steps is 0.001%. As Ash asks why the chances are low, Poipole wanders off to doodle Pikachu's face on a wall. Unexpectedly, Viren walks by and is infuriated by Poipole's doodle on his newly constructed wall. Ash apologizes and attempts to wipe it off with his hat until he realizes who he's talking to. Ash seemingly recognizes Viren but reveals that he actually doesn't. Then, Viren recognizes Ash as Ash Royal from the Battle Royal, and Ash calls him "Mister Greedy Creep". Viren gets mad and reminds Ash who he actually is. Ash asks Viren what he's doing and Viren tells Ash that he's building the Viren Tower, a resort with a high-class boutique, restaurant, and hotel. But while Viren continues to talk, Ash stops listening to check out another of Poipole's scribbles, which turns out to be an ugly picture of Viren. Ash comments that the drawing really looks like Viren, which the latter angrily denies. Then, Burnet calls Ash to tell him that they're leaving and Ash rejoins the Professors. As Ash leaves, Viren tells him not to come back, and Poipole waves him goodbye. When Viren returns to his construction site, he finds his henchmen slacking off and shouts at them to get back to work. Later that night, an Ultra Wormhole opens up, and a giant, black, box-like object emerges from it, falling to the ground.
The next day, at the Pokémon School, the kids are surprised to see the giant object, and Ash and Kiawe believe Kukui prepared it for them. Ash goes first and runs up to it, but then an Alolan Diglett pops out of the ground, making him trip and slam face-first into the object. Kiawe then goes next, but as he gets close to the top, the object shifts one of its tiles to reveal a blue eye. When Kiawe gets to the top, the tile that he touches falls down, causing Kiawe to fall in. Kiawe screams at the sight of many eyes looking at him before being ejected. When his classmates run up to him, Kiawe is still in shock and muttering under his breath. At Mallow's request, Tsareena tramples Kiawe with her foot to calm him down. Mallow comments that the force was a bit too much, but Kiawe is snapped out of his delirium. As Kiawe wonders what the giant object could be, Komala rings the bell furiously, and Kukui comes out to tell the class about a new Ultra Guardians emergency.
At the base, the Ultra Guardians are briefed on the new Ultra Beast, Stakataka, which is the same giant object outside the school. Back on the field, the Ultra Guardians are surprised that the giant object is a Pokémon. Ash throws a Beast Ball at Stakataka, but it dodges by rearranging its own body. Then, Kiawe throws a Beast Ball with his "Inferno Overdrive Ball" serve, but Stakataka moves its tiles, causing the Ball to hit a tree and ricochet right back into Kiawe's face, as a PokéBase Scyther randomly appears and calls a strike on Kiawe. Lillie suggests that they weaken Stakataka with a battle. First, Pikachu ensnares Stakataka in an Electroweb, Snowy follows up with a Powder Snow, Togedemaru uses Zing Zap, Popplio performs a Bubble Beam, followed by Tsareena's Trop Kick and Marowak's Bonemerang. Despite the joint effort, Stakataka is unfazed and breaks free of its restraints. Lillie suggests a new plan, and the group follows suit. Ash, Kiawe, Lana, and Mallow surround Stakataka and throw Beast Balls at it. However, Stakataka once again rearranges its body, causing the Balls to miss their target and hit the throwers. Ash and Kiawe still aren't ready to give up and continues to throw Beast Balls at Stakataka, which goes on until evening. The Ultra Guardians are left exhausted, and Lillie contacts her mother to tell her that they weren't able to catch Stakataka. Lusamine decides that they should just observe the situation in the meantime and try again the next day.
The next day, at Viren's construction site, a large object covered by a tarp is being loaded. Viren tells his henchmen to be careful with it, stating that they'll pay if it breaks. Then he tells them that it was nice of them to get a pedestal for the object and says that he'll pay them a bonus, but the henchmen are unsure who prepared the pedestal. Meanwhile, Ash arrives at the Pokémon School and Lillie soon informs him that Stakataka has disappeared. Lillie notices square markings on the ground that she believes might be footprints. Then, Komala rings the bell again as Kukui tells the kids about an Ultra Aura reaction in the city. The Ultra Guardians mount their Ride Pokémon and set off for Hau'oli City. The Ultra Guardians arrive at the location of the Ultra Aura: Viren's construction site. Kiawe burns up with anger at the mere mention of Viren as the Ultra Guardians decide to investigate. Viren and his henchmen notice the Ultra Guardians and tell them to leave, ignoring their warnings about an Ultra Beast. As the Ultra Guardians look for Stakataka, Poipole notices the box containing the pedestal and Ash attempts to open it up, only for Viren to lower the covered object onto the pedestal, and the pedestal reveals itself to be Stakataka.
Viren unveils the tarped object to reveal that it's a gold statue of himself. The Ultra Guardians are unimpressed as Kiawe calls it tacky, Lana says the statue doesn't look like Viren, and Mallow states that he's slimmed down too much. As Viren brags about his statue, Stakataka starts shaking and its eyes turn from blue to red as it gets up and starts violently thrashing around. Viren is too busy demanding that Stakataka stop moving around that he doesn't notice one of Stakataka's legs about to crush him, so Kiawe has to kick him away. Kiawe mockingly asks Viren if he's alright, to which Viren sarcastically replies that he's glad Kiawe is worried about him. As Ash asks why Stakataka is suddenly rampaging, Lusamine and Wicke call the Ultra Guardians to inform them that Stakataka hates having anything on top of itself and will try to shake it off. Kiawe heeds the advice and sends out Marowak to have it use Bonemerang on the statue. However, the attack is blocked by Viren, who is subsequently knocked out. However, Kiawe is still happy that Viren got hit and recalls Marowak while Mallow and Lana drag Viren away from Stakataka. Ash and Pikachu attempt to climb Stakataka's legs, but Stakataka shakes them off. Sophocles sends out Togedemaru who tackles Ash and Pikachu out of the way so they don't get crushed by Stakataka.
As the Ultra Guardians discuss a new plan, Ash suggests that they jump on it, and Kiawe sends out Turtonator to have it hold up a wooden board as a makeshift springboard. Ash runs up the board but ends up stepping on Turtonator's spikes, triggering Shell Trap. Surprisingly, the explosion manages to send Ash and Pikachu on top of Stakataka. Ash tries to push the statue off but is unable to do so as it's glued on to Stakataka, so instead, he has Pikachu use Iron Tail to knock it off. However, Stakataka continues to rampage and as Ash questions why it's still angry, Kiawe reminds Ash that it's because he and Pikachu are now on top of it. Ash asks Stakataka to calm down and after thrashing about a bit more, Stakataka's eyes turn back to blue and it calms down. It retracts its legs, accidentally trapping Viren in itself, and when Viren wakes up, he is scared by Stakataka's multiple eyes watching him and asks for help. Lillie theorizes that because Ash successfully rode Stakataka, it developed respect for him. Ash asks Stakataka if he can catch it, promising to return it to where it came from. Stakataka tears up in joy and allows itself to be caught. Then, Viren recovers to see his damaged statue which his henchmen state that it looks just like him, much to his annoyance. Viren calls off Viren Tower in favor of forming a PokéBase team and building his own Viren Stadium as the Ultra Guardians fly away.
That evening, back at the Pokémon School, an Ultra Wormhole opens up and Ash sends out Stakataka, allowing it to return home. After the Ultra Wormhole closes, Ash's friends comment on his earlier jump with Turtonator's help. Ash declares that he'll leap up to 50 steps and calls for Turtonator. He accidentally touches Turtonator's spikes, causing another explosion that burns the Ultra Guardians, but they all laugh it off.