At Cerise Park, Goh and Raboot are feeding and cleaning the Pokémon. After brushing his Sentret and Stantler, Go offers to brush Raboot, but it immediately walks off. Meanwhile, Ash has Riolu practice its Vacuum Wave technique while Mimey defends. The training session is interrupted after Goh reminds Ash that he is supposed to be helping all the Pokémon at the Park. Ash rushes over, apologizing for his forgetfulness. He agrees to do whatever task is left, to which Goh sets him the task of brushing Darmanitan's teeth.
Goh's Beedrill flies over and spots an empty tray, meaning it has missed out on breakfast. It disturbs Oddish and Nidoran♀'s sleep to demand answers. The pair try to explain; however, Beedrill is too infuriated and hungry to listen to reason. As it starts waving around its stingers, Stantler and Nidoran♂ step in and defend the others from Beedrill. Ash rushes over to the commotion and quickly realizes Beedrill must still be hungry. Nearby, Goh is forced to intervene after his Grimer, who also missed out on a feed, confronts some of the Bug Pokémon. Ash and Goh regroup, both reporting that the food trays are all empty. Several days pass, and the food supplies at Cerise Park continue to be disappearing at a rapid rate. Watching through the security monitors, Goh and Ash feel concerned by the growing aggression, noting that they feed everyone enough food already. The boys suspect that someone is behind the food theft. Ash thinks his tricky Gengar might be behind the prank, to which it appears behind him and attacks him with a Shadow Ball. Professor Cerise is intrigued, and adds that even in the small vicinity of Cerise Park all the Pokémon have formed communities. The Water Pokémon live in the pond, a small group has gathered around Golurk, while Misdreavus and Sandile keep to themselves. Most concurringly, Cerise says that the large Bug group look like they will soon clash with the Normal and Poison types. Ash and Goh decide that they will have to act quickly to avoid conflict, so they plan to sleepover in the Park while they investigate the cause of the disappearing food.
In Cerise Park, Misdreavus tries to scare Parasect for the fun of it, only to get attacked for the prank. Meanwhile, as Sandile's stomach grumbles, it bumps into Darmanitan, which has entered its Zen Mode. It lashes out at Darmanitan, only for the Blazing Pokémon to transform into its Standard Mode and blast Sandile away with Overheat. Misdreavus and Sandile are sent flying into each other, and after dodging an Air Slash from Scyther, the unlikely duo decide to join forces. The hunger crisis hasn't affected Goh's three Cascoon, who are soundly asleep to save energy and beginning to glow in preparation for evolution.
By nightfall, Ash and Goh have set up camp in the park. They have laid out some trays of food hoping to catch the gluttonous culprit in the act. Go and Raboot take the first watch shift, where no one takes the bait. Ash, Pikachu, and Riolu takeover for the rest of the night, and again nothing happens. By morning, however, Ash and Goh find the food has been taken, plus the Bug and Normal-Poison groups are about to clash. Butterfree and Venomoth launch a cloud of Stun Spore, which Grimer counters with a Poison Gas. Tensions escalate into an all-out brawl, which Pikachu, Riolu, and Raboot can't stop. Ash spots his Dragonite flying over and orders it to intervene. However, Dragonite snatches up Goh, Ash, and their Pokémon partners as it carries them to a vantage point to allow the Pokémon to resolve the matter for themselves. Noticing the fighting, Skwovet and Cubone alert the Golurk group, to which they decide to intervene. As Darmanitan launches an Overheat, Scyther blocks the attack, bolstering the Bug side's morale. Darmanitan and its allies flee to the pond, only to be stopped by Misdreavus and Sandile. The mischievous pair frightens their victims with Sandile seemingly breaking a tree in half; though the trunk had been destroyed by Scyther's earlier Air Slash. As Misdreavus and Sandile laugh amongst themselves for pulling off the prank, Scyther and its Bug army arrive on the scene. Darmanitan and the others are frightened and push Sandile forward to show Scyther some of its brute power. In a twist, Misdreavus and Sandile join with the Bug types. Butterfree and Venomoth use Stun Spore on Darmanitan's forces, and incidentally the pond Pokémon as well. The Water-types retaliate, with Dewgong firing off an Ice Beam as a warning. However tensions peak, with the fight now turning to a four-sided affair.
Ash and Goh arrive at the pond to see that another fight has erupted. Scyther counters another Overheat from Darmanitan, sending the attack towards the still sleeping Cascoon trio. Golurk shows up just in time and blocks the wayward attack. Unexpectedly, Golurk's seal on its chest comes off and unleashes incredible power. A red beam of light blasts into the sky, causing dark clouds to fill the sky followed by a torrential downpour. Goh thinks this might be Golurk's Rain Dance, though Ash thinks otherwise and consults his Rotom Phone for answers. The boys are alarmed to learn that Golurk's now-missing chest seal has unleashed uncontrollable power, so they rush to stop the giant. Golurk's friends, Cubone, Skwovet, Pidgey and Farfetch'd, arrive with the broken seal and offer their assistance. Ash and Goh plan to distract Golurk with their attacks while the others reseal Golurk. Pikachu uses Iron Tail and Raboot follows on with an Ember attack. Riolu tries to help, but its Fighting attacks prove useless against Golurk, who is part Ghost-type. Golurk's friends manage to fly up and place the seal on its chest, with Farfetch'd and Cubone hitting the two rivets into place. Golurk instantly reverts to its normal state, though the stormy conditions continue.
Goh is particularly concerned about his three Cascoon, who may not evolve because of the bad weather. The rain also causes the dam walls to break, flooding the rest of Cerise Park. The tree holding the three Cascoon begins to shift from the torrent, so Golurk and Ash’s Dragonite rush to support it. Goh orders his Dewgong and Tentacool to freeze over the floodwaters, allowing the boys to rush over to the scene. The other Pokémon set aside their differences and all help the Cascoon by supporting the tree. Soon, the Cascoon burst into an intense blue light and emerge as three Dustox. Together, the newly-evolved Dustox use Sunny Day to vanquish the dark clouds and usher in the daylight.
Everyone's stomachs grumble, so Ash and Goh get the team some food to enjoy. The boys are glad that tensions have settled, and impressed that everyone worked together to help the Cascoon evolve. A sudden landslip leads Ash and Goh to uncover the hidden hoard of food, and the culprit, Goh's Skwovet returns to the nest to add more food to it. Goh is stunned by the revelation, and his Pokédex confirms that storing food is typical behavior for Skwovet. With that, Ash and Goh decide to increase food supplies to keep Skwovet's hoard full, and the other Pokémon fed.