Ash's run in the World Coronation Series has led him to Sunyshore City in the Sinnoh region, where he's due to have an Ultra Class match against Volkner, the local Gym Leader whom he's battled before while he was journeying across Sinnoh. Walking together towards the battlefield where their match will take place, both Ash and Volkner are excited to get to battle each other again. Volkner notices Ash wearing an Alolan Z-Power Ring on his wrist, and is intrigued by the Z-Crystal on it, which Ash explains to be one specifically for him and Pikachu.
Goh and his Grookey are in the stands, ready to cheer for Ash. Ash and Volkner enter the field and are introduced, although the applause Ash receives is not even close to the one Volkner gets. At Drone Rotom's signal, the first Pokémon are sent out, with Ash choosing Lucario and Volkner going with Luxray. Volkner begins the match by having Luxray set up an Electric Terrain. Lucario attacks with Aura Sphere, but Volkner counterattacks with Rising Voltage, which both blocks the Aura Sphere and strikes Lucario, its power being increased thanks to Electric Terrain being in effect. Ash quickly recalls Lucario and sends out Gengar in its place. With its agile movements, Gengar easily dodges Luxray's Snarl before throwing it around with Psychic and hitting it with Night Shade.
Seeing that Luxray is outmatched against Gengar, Volkner recalls it and sends out his Fan Rotom, which is fast enough to match Gengar's unpredictable movements. Rotom uses Air Slash, which Gengar counters with Night Shade. Next up, Gengar attempts to use Ice Punch, but Rotom avoids it and uses Thunder Wave, paralyzing Gengar. Rotom follows up with Hex, using its opponent's status condition to deal heavy damage on Gengar. While Gengar attempts to stay standing, it quickly collapses, fainting from the damage it has taken. Ash recalls Gengar and thanks it for a good match, just as the Electric Terrain wears off.
Ash next calls forth Pikachu, who steps onto the battlefield. Ash orders an Electroweb, a move that Volkner is surprised to see Pikachu using, successfully trapping Rotom. However, just as Pikachu starts following it up with a Thunderbolt, Volkner suddenly recalls Rotom and sends out Electivire to take the attack. As such, Pikachu's Thunderbolt ends up being completely absorbed by Electivire's Motor Drive Ability, leaving the Thunderbolt Pokémon unscathed and increasing its Speed in the process. Using the Speed increase to his advantage, Volkner has Electivire use Fire Punch, which strikes Pikachu before he can react. Ash has Pikachu use Iron Tail, but Electivire counters with its own Iron Tail, using both of its tails to overpower Pikachu's one tail and winning the clash.
With Pikachu getting overwhelmed, Ash withdraws him from the match for now and sends out Lucario. Lucario uses Aura Sphere, while Electivire uses Fire Punch, with both moves hitting the other and pushing both Pokémon back. Electivire follows up with Wild Charge, but Lucario's Double Team causes the attack to hit nothing but thin air. Lucario and all the Double Team clones use Aura Sphere, but Electivire uses its tails to hit them all back before using Thunder Punch, hitting Lucario and paralyzing it.
To Ash's surprise, Volkner suddenly recalls Electivire and calls out Rotom, using Hex to take advantage of Lucario's paralysis. With Lucario's endurance running low, Ash tells it to use Reversal. Enduring Rotom's Air Slash, Lucario executes the attack, striking Rotom with a devastating Reversal and taking it out of the fight. Volkner is impressed, even noticing that Lucario actually managed to shake off its paralysis while using the move. He next up calls out Luxray, who sets up Electric Terrain once again. The two Pokémon then attack with Aura Sphere and Rising Voltage, striking each other simultaneously. For a few moments, they stare each other down, before succumbing to the damage they already have sustained and fainting on the spot, resulting in a double knockout.
Both sides are now down to their last Pokémon, so Pikachu and Electivire return to the battlefield once again to face each other. With Motor Drive limiting the move options that Pikachu can use, Ash goes for an Iron Tail, but Electivire easily overpowers it with Wild Charge, not even flinching at the recoil damage as the Electric Terrain's effect fades away again. Another Iron Tail clash follows, but this time, Pikachu manages to land a hit on Electivire's head, causing the big Pokémon to stumble.
Noticing that Pikachu is eager to use an Electric move to finish the match, Ash tosses his hat to him and starts drawing power from his signature Z-Crystal, the Pikashunium Z. His and Pikachu's signature Z-Move, 10,000,000 Volt Thunderbolt, flashes across the battlefield and strikes Electivire, who puts Motor Drive into overdrive in an attempt to absorb the powerful move. Eventually, a big explosion ensues, and when the smoke clears, Electivire falls over and faints, the Z-Move having overcharged its Motor Drive. As such, Drone Rotom declares Ash the winner.
With his victory, Ash finally earns an applause to match the one Volkner had received earlier, and his rank rises from 99 to 64. Volkner walks up to Ash, expressing how impressed he was of the 10,000,000 Volt Thunderbolt. Ash says that he had chosen to finish the match with his strongest Electric move the moment he had learned that he'd be facing Volkner. Volkner predicts that Ash will become the "eye of the storm" that will shake up not just the Ultra Class, but even the Master Class, revealing that Sinnoh League Champion Cynthia is part of the Masters Eight.