As a new day begins in the Galar region, Ash and Lucario arrive at the city of Hammerlocke, eagerly waiting for their World Coronation Series entrance battle. Arriving in front of the Hammerlocke Stadium, Ash is greeted by his opponent and the local Gym Leader, Raihan. They both express their determination to win, only to be interrupted when they notice none other than Leon waking up from behind a nearby bush, having come early so he wouldn't miss the match. He encourages Ash and Raihan to give their all in the upcoming battle.
Inside the Stadium, the stands are filled with lots of people eager to witness the last entrance battle of the season, with Goh, accompanied by Cinderace and Grookey, sitting amongst them. Ash and Raihan enter the battlefield and are introduced to the audience, with Raihan receiving plenty of cheering from the people of his hometown. Referee Dan explains that the match will follow the Masters Eight Tournament rules, with both sides using three Pokémon each and being allowed to switch them at any time as many times as they want. In addition, either side may only use one of either Mega Evolution, Z-Moves, or Dynamax per battle, with Goh predicting that Ash is going to use Mega Evolution with his Lucario. At Dan's signal, both sides send out their first Pokémon. Ash's choice is Dragonite, while Raihan goes with Flygon, making the first round a clash between Dragon types.
Raihan makes the first moves by ordering a Dragon Claw, while Dragonite uses the time to set up a Dragon Dance, increasing its Attack power and Speed. With its increased Speed, Dragonite evades Flygon's subsequent Steel Wings easily. Raihan admits that Ash has trained his Dragonite well, but also reminds him that he's a Dragon-type expert, and orders a Sandstorm, which envelops the entire field. With its vision blinded by the sandstorm, Dragonite is struck by a Dragon Claw and a flurry of Steel Wings from Flygon as the Mystic Pokémon hides itself in the swirling sand, which is also slowly dealing damage to Dragonite over time. Ash decides on a new strategy and orders Dragonite to use Draco Meteor, which sends meteors raining all over the battlefield. One of them manages to hit Flygon, giving away its location and allowing Dragonite to attack it with Hurricane and Dragon Claw before it hides in the sandstorm again. Ash prepares to repeat his Draco Meteor strategy, but Raihan declares he won't fall for the same trick twice and has Flygon strike Dragonite with Steel Wing before the Draco Meteor can go off, taking Ash's Pokémon out of the fight.
After recalling Dragonite, Ash chooses Gengar as his second Pokémon. While Gengar manages to evade Flygon's Steel Wing, its Ice Punch fails to land, leaving Gengar just as vulnerable against Flygon's hit-and-run strategy as Dragonite had been. Following a series of Dragon Claws, Gengar is struck by a super effective Crunch, dealing heavy damage to it. Goh grows worried, since losing Gengar now would leave Ash with just one Pokémon against Raihan's three, putting him at a severe disadvantage. As Gengar wearily stands back up, Raihan asks Ash why he wants to battle Leon, because to him, the desire to challenge Leon needs to be supported by a desire to defeat him, a desire that he has in spades. Ash, however, declares that he too wants to defeat Leon, and refuses to lose here in order to realize that goal.
Seeing that Gengar is getting tired, Ash changes his initial plans, apologizing to Lucario for not being able to Mega Evolve it now as he slips on his Dynamax Band and Gigantamaxes Gengar. Using Gigantamax Gengar's giant mouth, Ash has it suck away the sandstorm, leaving Flygon exposed and wide open for G-Max Terror, which scores a direct hit. Raihan attempts a counterattack with Crunch, but Flygon is stopped in its tracks by Max Starfall, defeating it and evening the odds.
Raihan selects Goodra to be his second Pokémon and has it use Rain Dance, further demonstrating his weather-based strategies. Utilizing the rain to its advantage, Goodra launches a rapid-fire offensive with Thunder, Surf, and Hydro Pump, all of which deal devastating blows. Ash considers recalling Gengar, but as he sees its willingness to keep going, Ash decides to keep it out. Goodra attempts another Surf, but this time, Gengar is able to deflect it with its tongue. Gengar attacks with Max Starfall, while Goodra uses Hydro Pump, both moves hitting their targets. Gengar reverts to its normal size as both Pokémon collapse, resulting in a double knockout and leaving both Trainers with one Pokémon each.
Both sides recall their Pokémon and send out their last fighters, Lucario and Duraludon. While Ash has already used his once-in-a-battle power-up, Raihan still has his Dynamax to use, and he puts it to use by immediately Gigantamaxing Duraludon. Lucario uses Double Team to confuse Duraludon, before using Aura Sphere, which, however, doesn't faze the Gigantamax Pokémon at all. After a second Aura Sphere provides equally lackluster results, Raihan starts his counteroffensive with Max Steelspike, which Lucario is unable to completely avoid. Raihan then has Duraludon unleash its strongest attack; G-Max Depletion, which envelops Lucario in a swirling tornado of energy. To Raihan's surprise, however, Ash is perfectly calm about this situation, as is Lucario, who is standing still inside the vortex and charging up an Aura Sphere.
Ash and Lucario's Auras are in perfect sync as Lucario raises the growing Aura Sphere over its head, causing the G-Max Move to dissipate around it. Goh realizes that this Aura Sphere is similar to what Lucario did after its training with Greninja, except that it's even bigger. Drawing power from the Aura of its teammates, Goh and his partners, and even Greninja all the way back in Kalos, Lucario's Aura Sphere grows to a gigantic size, and Ash dubs it "G-Max Aura Sphere". Duraludon attempts a counterattack with Max Rockfall, but Lucario's attack easily powers through it and strikes the Gigantamax Pokémon head-on, causing it to topple and revert to normal size. Dan judges Duraludon as unable to battle, meaning that Ash has won the entrance battle. Ecstatic, Ash runs over to Lucario and congratulates it on a well-fought battle. Raihan approaches Ash and admits that he lost. After taking a selfie with Ash, Raihan swears to defeat both him and Leon someday and tells him not to lose until then.
With the season's final entrance battle completed, the eight Trainers advancing to the Masters Eight Tournament have been decided. In addition to Ash, who is now ranked eighth, said Trainers include Unova Champion Iris; Lumiose Conference winner Alain; Kalos Champion Diantha; the combined Champion of Kanto and Johto, Lance; Hoenn Champion Steven Stone; Sinnoh Champion Cynthia; and Leon, the undefeated Monarch and Galar Champion.