A news crew continues to report on the events occurring around Hammerlocke Stadium and the Dynamax outbreaks across Galar. Meanwhile, Jessie, James, and Wobbuffet are still fleeing from the rampaging Gigantamax Meowth. Luckily, a mention of Giovanni snaps Meowth back to his senses, and he starts to go after Eternatus. As Meowth scales the stadium complex, his teammates grab hold of his tail. Already on the rooftop, Leon prepares to Gigantamax his Charizard; however, this fails, as does Meowth's attempt to use G-Max Gold Rush, due to Eternatus absorbing all the Galar particles in the vicinity. The Gigantic Pokémon then launches a Dynamax Cannon, which sends Team Rocket blasting off, before continuing to charge itself with Galar particles.
On the battlefield, Chairman Rose is pleased to see Eternatus absorbing the Galar particles to assume its final form. Ash is determined to end the chaos, so he orders Riolu and Pikachu to attack. Rose's Ferrothorn blocks with Iron Defense and Copperajah uses Heavy Slam on its opponents. Riolu prepares to land a counter Force Palm, only for Ferrothorn to intervene while Copperajah tries another Heavy Slam. Ash realizes Rose's strategy involves synchronized offense and defense, so he tries to separate Rose's Pokémon with Pikachu's Quick Attack and Riolu using Double Team. Rose then orders both of his Pokémon use Power Whip, managing to corner Pikachu and Riolu. Ash orders his pair to leap at the last moment, leading Rose's Copperajah and Ferrothorn to instead strike each other down with Power Whip. Rose is stunned by the counter tactic.
Meanwhile, Goh is facing Oleana in battle inside the stadium foyer. Goh's Raboot launches an Ember, which is knocked back by Oleana's Milotic using Water Pulse. Raboot tries a flurry of Ember attacks, though another Water Pulse from Milotic lands instead. She remarks on Goh's weak performance, admitting that he is rather foolish for thinking he could even defeat Eternatus. She orders Goh to stop wasting her time and simply forfeit. Goh, however, refuses and orders another Ember. Milotic again counters with Water Pulse, landing a blow on Raboot as well. Goh decides to switch things up, but Raboot launches another Ember, insistent that it wants to only battle using Ember. Goh concedes, reflecting on Raboot's performance against Flygon. Oleana scores another Water Pulse hit on Raboot and orders it to use Aqua Tail.
Eternatus suddenly launches a powerful Dynamax Cannon at the Hammerlocke Stadium complex, and the other battles pause momentarily. Pikachu narrowly evades the attack, leaping into Ash’s arms for safety. Rose orders his Pokémon to use Power Whip, though Riolu leaps in front to defend its Trainer and Pikachu. Riolu manages to stave off the blows with its paws and evolves into a Lucario to bolster its strength. Ash first calls for a Vacuum Wave, but Lucario uses its Aura to communicate with him, so he instead tells it to use Aura Sphere, defeating Rose’s Pokémon with ease. Ash then rushes off to help Leon take on Eternatus, while Rose rushes to tend to his defeated Pokémon.
Goh, meanwhile, considers a way to win the battle with Ember, by aiming the attack at the walls and ceiling from all angles. Raboot fulfills its Trainer’s request, landing several Ember attacks on Milotic before evolving into Cinderace. Taking a moment to scan it with his Rotom Phone, Goh orders Cinderace to launch its new attack, Pyro Ball. The attack hits its mark and Oleana's Milotic is unable to battle. Raihan, meanwhile, easily defeats the group of Macro Cosmos agents after Sonia with Duraludon's Breaking Swipe. Sonia thanks Raihan for his help. He replies that while he would ask her on a date, however, he has to turn his attention to defeating the rampaging Dynamax Pokémon across Galar first. While Raihan leaves the area, Sonia turns her own attention to Eternatus.
Ash and Goh soon reach the Tower Summit, where Leon and Charizard continue to battle Eternatus. The boys take a moment to marvel at each other's newly-evolved Pokémon before returning to the real situation at hand: defeating Eternatus. Leon focuses his attention on Eternatus's head to stop its attack and has Charizard use a flurry of Air Slash attacks. As Eternatus appears to falter, Leon throws an Ultra Ball at it, momentarily sucking it in. However, Eternatus soon breaks out, with a powerful wave of energy knocking the boys down. Leon is forced to recall his Charizard before fainting from exhaustion. Eternatus then flies up into the sky and transforms into its larger Eternamax form. Watching from his helicopter, Chairman Rose is thrilled by the development while Oleana is taken aback by it. Ash and Goh step up to take on Eternatus, but it is unfazed by their efforts and retaliates with Eternabeam. While Pikachu, Lucario, and Cinderace lay strewn about from the powerful attack, Goh cries out to them.
The Rusted Sword and Rusted Shield suddenly glow blue and red respectively, taking Ash and Goh by surprise. Goh explains that he found them in the Slumbering Weald. Sonia reaches the rooftop and rushes to attend to her injured friend Leon. Eternatus then launches another Eternabeam, which again causes the Rusted Sword and Shield to glow. Ash and Goh realize they must fulfill the ancient legend, so they raise their armaments to defend Galar from Eternatus's evil power. With this, Zacian and Zamazenta awaken at the Slumbering Weald and come to their aid, taking possession of the Rusted Sword and Shield, respectively, and transforming to their Crowned Sword and Crowned Shield forms. Zacian strikes with Behemoth Blade and Zamazenta follows on with a Behemoth Bash. Ash and Goh order Pikachu use Thunderbolt, Lucario uses Aura Sphere, and Cinderace strike with Pyro Ball. The attacks hit before the Hero duo launch their own combined attack to exhaust Eternamax Eternatus. Goh sees his opportunity, and with Ash's help, hurls a large Poké Ball and successfully catches Eternatus. Goh's Rotom Phone updates with information on Eternatus, and the boys cheer. Zacian and Zamazenta quickly leave the area, leaping up into the sky and clearing away the dark clouds. The Dynamax Pokémon also return to their usual forms, ending the chaos across Galar. As the Rusted Sword and Shield return to Ash and Goh's possession, Leon takes the opportunity to thank them for helping save Galar.
Sometime later, Professor Magnolia and her granddaughter Sonia update each other on the situation across Galar. Chairman Rose's whereabouts are a mystery, while Leon tries to track him down. Eternatus has since been sealed deep in the earth, but Magnolia admits it still poses a potential future threat. Sonia, meanwhile, has been given the title of Pokémon Professor, with her very own white lab coat, and tasked with protecting Galar from future harm. At the Slumbering Weald altar, Ash and Goh return the Rusted Sword and Shield to their rightful place and take the opportunity to thank the Hero duo for their help. As the boys leave the altar, unknown to them, Zacian and Zamazenta appear momentarily to see them off.