The second battle of the Pokémon World Coronation Series Masters Eight Tournament's first round is about to get underway as Lance and Diantha enter the Wyndon Stadium battlefield. In the stands, Ash tells Goh and Hop how he's actually battled against Diantha before, much to Hop's amazement. Elsewhere in the stadium, Team Rocket is continuing their live coverage of the event, although Jessie refuses to acknowledge Diantha as a superior actress to her. Both Champions give speeches about how they shoulder the hopes of the Trainers of their respective regions and look forward to facing each other. Dan explains the usual rules: the battle will be three-on-three, with substitutions allowed to be made at any time. Moreover, each competitor may only use one of either Dynamax, Mega Evolution, or Z-Moves per battle.
At Dan's signal, the first pair of Pokémon is sent out. Lance leads with his Dragonite, while Diantha's first choice is Aurorus. Lance makes the first move by ordering a Hyper Beam, but it ends up being heavily weakened by Aurorus's Light Screen. As Dragonite is forced to recharge after using Hyper Beam, Diantha uses the opportunity to hit Dragonite with a supereffective Blizzard. Despite taking heavy damage from the attack, Dragonite is able to endure it, and, immediately after it has finished recharging, deals supereffective damage of its own with Body Press. The second Body Press, however, is softened up by Reflect, giving Aurorus a double layer of protective barriers to hide behind. In the locker room, Alain notes that the screen moves will fade eventually and only provide temporary defenses. Based on the current situation, both Steven and Cynthia believe Diantha has the advantage at the moment. Undeterred, Lance has Dragonite attack with Twister, while Aurorus uses Rock Slide. Both attacks hit their mark, but unlike Dragonite, Aurorus is unable to withstand the hit and faints, giving Lance the first knockout of the match.
As Diantha recalls her fainted Pokémon, Lance decides to do the same and withdraws Dragonite. Diantha's second Pokémon choice is Gourgeist, which elates Jessie, as she once owned a Gourgeist as well. Against the Ghost/Grass opponent, Lance chooses his Red Gyarados. Gourgeist begins the round by using Trick-or-Treat. Hop explains to Ash and Goh that Trick-or-Treat is Gourgeist's signature move, which adds Ghost to the opponent's type, meaning that Gyarados is now weak against Ghost-type moves. Gyarados attacks with Aqua Tail, which pushes Gourgeist back, even through Reflect. Knowing that the effect of Light Screen will end soon, Lance orders a Dragon Pulse. Before the attack can go off, Gourgeist attacks first with Shadow Sneak, which, thanks to Trick-or-Treat, deals big damage on Gyarados. The Dragon Pulse is still successfully fired, however, hitting Gourgeist just as Light Screen fades away. Lance aims for a finishing blow with Ice Fang, but Gourgeist uses Phantom Force to evade it. Although Gyarados manages to hit Gourgeist with a Dragon Pulse afterward, the damage from Phantom Force is too much for it to withstand and it faints, evening the odds and making Team Rocket shed tears of joy at seeing a Gourgeist succeed.
Lance's third Pokémon is Hydreigon, which Diantha also feels prepared for, having Gourgeist use Trick-or-Treat on it. Ignoring this, Lance has Hydreigon use Dark Pulse. Not only does the attack hit its mark just as Reflect fades away, but it also causes Gourgeist to flinch, leaving it open for another supereffective Dark Pulse. The attack is enough to defeat the Pumpkin Pokémon, much to Jessie's dismay. Talking to Gyarados's Poké Ball, Lance thanks it for enabling this victory. Diantha's third and final Pokémon is her ace, Gardevoir, whom she immediately Mega Evolves. Diantha orders a Shadow Ball, which Hydreigon successfully counters with Tri Attack. Lance follows up by calling for Flash Cannon, which ends up being easily dispersed by Gardevoir's Psychic power. Gardevoir launches a Moonblast, and though Hydreigon attempts to withstand the attack, it is engulfed by a massive explosion and knocked out, meaning that both Trainers now have just one Pokémon left.
Dragonite reenters the battlefield, full of confidence. Lance wastes no time in using his Dynamax Band to Dynamax Dragonite, increasing its stamina in the process. Backstage, Alain notes that, unlike Mega Evolution, Dynamax has a time limit, which could end up being a decisive factor. Gardevoir's Moonblast powers through Dragonite's Max Hailstorm and scores a hit, which the Dragon Pokémon successfully endures. Max Hailstorm's secondary effect results in hail starting to fall over the battlefield, slowly chipping away at the stamina of both Pokémon. Confident that Dragonite can handle it, Lance orders a Max Strike, which engulfs Gardevoir, but even while being pummeled by the Max Move, Gardevoir is still able to use Shadow Ball. Dragonite counters with Max Wyrmwind, which, while useless against a Fairy type like Gardevoir, is still able to completely stop and dissipate the Shadow Ball before it can make contact. Both Diantha and Ash surmise that Lance is trying to keep Dragonite standing so he can attack as soon as its Dynamax state ends. This is proven true moments later as Dragonite returns to normal size and fires a Hyper Beam. Diantha is unconcerned and has Gardevoir attack with Moonblast, evading the Hyper Beam and dealing the finishing blow on its immobilized opponent. Dan declares Diantha the winner of the match, meaning that she'll be advancing to the semifinals to be Leon's next opponent, although Hop is confident that his brother is going to win. In Diantha's post-battle interview with Team Rocket, Diantha thanks her fans in Kalos, while Jessie gets up in her face and insists that she use Gourgeist as her final Pokémon in the next battle, much to Diantha's confusion.
Backstage, Ash meets with Lance, who seems positive, despite his defeat, and tells Ash to hang in there before leaving. As he watches Lance walk away, Ash is approached by a very excited Iris, who is eager to let loose after witnessing two heated battles. Ash wishes her good luck against Cynthia, and she eagerly rushes to the battlefield. Once both competitors are in place, Dan gives the signal to send out the first Pokémon. Iris's lead is her trusted first partner Pokémon, Excadrill, which Ash is excited to see again. On the opposite side of the field, Cynthia sends out Gastrodon as her first Pokémon, marking the start of the battle between the Sinnoh and Unova Champions.