Kiawe is about to take a break from work on Paniola Ranch when his sister Mimo comes rushing into the barn to alert him to Marowak's misbehavior. Kiawe, Mimo, and Turtonator rush over to see Marowak being knocked into the air by some of the Tauros herd's powerful kicks and horn attacks. When Kiawe tells Marowak that it never seems to learn, Marowak headbutts Turtonator but gets stuck in the shelled Pokémon's chest opening. Kiawe separates the two Pokémon, and Mimo scolds Marowak for its aggressive demeanor.
Kiawe looks into the distance, noticing something moving. A golden car speeds along the dirt roads, almost hitting some crossing Mudbray before coming to an abrupt stop on Kiawe's family property. A man emerges from the vehicle, accompanied by an Electivire. A Herdier starts barking, alerting Kiawe to the unwelcome visitors. Kiawe manages to calm down Herdier, and his parents arrive on the scene. The man dismisses Kiawe, and immediately introduces himself to Kiawe's parents as Viren, the president of the Rainbow Happy Resorts. He quickly clarifies his intention, to buy up and develop the vacant land for a resort hotel that would attract city folks. Sima and Rango tell Viren to leave as they are not interested in selling the land. Viren laughs and begins to return back to his car, noticing it has been covered in mud by the Mudbray. His Electivire returns to its Poké Ball, and his henchmen open the car door for him, before they quickly move off the property. Kiawe and family return to their work. Meanwhile, Viren makes a phone call in the car, announcing to someone on the other end to advance the development plan to the next phase. Later, Kiawe rushes to a group of Miltank screaming at the sight of the empty river. Kiawe rushes into the family store, where his parents are already having an intense phone conversation to figure out what has happened to the river. It is revealed that Viren's company, the Rainbow Happy Resorts, had purchased the upstream rights to the water and constructed a dam.
Now, Kiawe is at school in a foul mood. Everyone else is keeping their distance, speculating as to why he is upset. Ash arrives on the scene, greeting his fellow classmates. Pikachu is greeted by an enthusiastic Togedemaru, causing the pair to roll on the ground; Poipole mimics this. Ash then spots the disgruntled Kiawe and gets him to talk. Kiawe reveals the latest development with the river dam. Sophocles searches online for information on Viren and his company, noting the rapid expansion and bad reputation for heavy-handed and dubious methods. Ash, Sophocles, Mallow, Lana, and Lillie agree to help Kiawe protect his farm.
The group quickly make their way to Kiawe's family farm via boat. Upon arrival, Kiawe's parents explain that their water problems have been solved, since a neighbor will lend some water to them. Whilst this trouble may have been solved, the others still insist they wish to help Kiawe's family out. Sima accepts the group's assistance, and says she will reward them with some homemade ice-cream, much to their delight. Lillie, Lana, Mallow, and their Pokémon mop the barn floors, while Ash and Sophocles push hay carts around. Pikachu rescues a curious Poipole, who is tugging on a Tauros' tail. Kiawe is in the midst of herding a group of Tauros towards water when he spots two men, one holding a shovel, with a Boldore and Roggenrola, intimidating some of the Miltank. The Miltank run off through a break in the farm fencing. Just as Kiawe confronts the two men, Viren and his Electivire emerge. An exchange of words leads to a battle between Kiawe's Marowak and Turtonator versus Viren and his henchmen. Meanwhile, Sophocles out of exhaustion, and having completed his tasks, lays on the clean barn floors. Ash and his friends assemble, and notice Kiawe is nowhere to be seen. They run in search of Kiawe.
The battle between Kiawe and Viren begins. Marowak's Bonemerang knocks Roggenrola to the ground before Turtonator can even send out its Flamethrower. Marowak uses its Bonemerang, this time hitting Boldore, causing Turtonator's attack to miss its target. Kiawe scolds Marowak for its lack of cooperation, and Marowak defiantly runs straight into Electivire's Thunder Punch. The attack hits, knocking Marowak to the ground just as Ash and Mimo arrive on the scene. Viren has Electivire use Thunder on Mimo and Ash, but Turtonator intercepts Electivire's attack, taking the full hit, and causing it to faint. Rotom Pokédex scan Electivire noting the electric Pokémon's strength. Marowak rushes in again, though the attack does nothing. With Turtonator knocked out and Marowak's thumbs up, Kiawe gets Marowak to perform Inferno Overdrive, though it fails to charge up, sending a powerless Marowak into Electivire's Thunder Punch, and Marowak faints. Electivire begins to walk towards Kiawe, who is attending to his fainted Pokémon, though Ash intercepts and the rest of his friends arrive on the scene. Viren quickly calls back his Pokémon, suggesting that the sale contract should be signed shortly before leaving the scene.
Night has fallen and the group have since retreated back to Kiawe's house, where the Pokémon are enjoying a fruit dinner. A defiant speech by Rango is met with praise from Sima and Mimo. Ash and his friends begin to get ready for bed, with Rotom, Pikachu, and Poipole already asleep. Kiawe walks outside to find Marowak training its skills. Kiawe interrupts Marowak's training regime to admit the reason for the botched Z-Move. Kiawe explains that he doubted Marowak, though he doesn't anymore. Staring at Wela Volcano, Kiawe proclaims his faith in his Pokémon and they begin to train together. Ash is about to join in the training session when Rango interjects, explaining that Kiawe needs the time to himself and his Pokémon.
The next day, Viren returns to the family farm, though Ash, his friends, and Kiawe's family are already waiting. Viren asks if the family have reached a decision. Rango initially steps in before Kiawe interrupts, stating that he will take care of the situation. Kiawe says that if Viren loses, he will forfeit his interests in the claim. Viren states that if he wins, Kiawe will cede his farm. Neither agree nor disagree with the statements, though a battle quickly ensues. Electivire's Thunder Punch temporarily leaves Marowak's right leg paralyzed, though it recovers. Marowak responds with an Iron Head, hitting Electivire in the chest. Viren gets Electivire to summon rain using Rain Dance, beating its chest to summon rain clouds. Rotom states the rain will put Marowak, a dual Fire and Ghost-type, at a disadvantage by weakening its Fire-type moves. Kiawe calls for a Flare Blitz attack followed by Shadow Bone. The Iron Head attack lands a hit, striking Electivire's shin and causing the Pokémon to tear up. Kiawe sees an opportunity, launching into his Firium-Z pose. The intense green-flamed Z-move blows Electivire away, to everyone's delight.
Despite his loss, Viren refuses to leave and signals to his associates waiting in the distance. A pair of heavy yellow digger trucks break through the farm fencing. However, they are interrupted by the arrival of Officer Jenny, who arrests Viren for forgery of land ownership documents, trespassing, and malicious destruction to property (both legal and private). Viren and his henchmen attempt to escape, though they are blocked in by Officer Jenny's Granbull and other police vehicles. Officer Jenny later reveals that her older sister is the Officer Jenny of Melemele Island. Simultaneously, Kiawe and Turtonator thank Marowak for its valiant efforts. The police officers leave with Viren in custody, the river's flow returns, and Sima and Mimo approach Ash and his friends with trays of ice-cream cones. To Kiawe's surprise, Marowak starts misbehaving again and is sent flying into the air by an angered Tauros herd.