The mysterious Masked Royal and his partner Incineroar star in the Battle Royal, an Alolan tradition in which four Pokémon battle until the last one standing is the winner. Ash, watching on TV, can’t wait to get in on the action—and the next day, he gets his chance!
At the Battle Royal Dome, Ash’s Litten charges right into the ring, determined to take on the impressive Incineroar. The Masked Royal accepts Litten’s challenge and invites Sophocles and Kiawe to round out the four. He defeats them all, but Litten is fired up—and during an unexpected rematch the next day, it evolves into Torracat!
Ash and his Pokémon watch a Battle Royal match on TV. The Masked Royal and his Incineroar are about to earn their twentieth consecutive victory, but they have to deal with three other Trainers first. Rotom explains to Ash that a Battle Royal is an Alolan tradition, where four opponents have a free-for-all battle. After Incineroar withstands attacks from Machamp, Primarina, and Decidueye, the Masked Royal uses his Z-Ring to use Incineroar's powerful Malicious Moonsault. The attack knocks all three opponents out, earning the pair their twentieth win. Professor Burnet arrives home, just as the Masked Royal announces that Trainers can challenge him in person tomorrow.
The next day, Ash arrives at the Battle Royal Dome on Akala Island where he catches up with all of his classmates. Meanwhile, Team Rocket is on the scene and their food truck business is slow. They overhear a man calling for a Battle Royal host and gladly volunteer themselves. Ash and his friends have since made it to their seats, just as the Masked Royal's appearance is announced. His Incineroar somersaults into the ring before Meowth calls for any battle volunteers. The crowd all enthusiastically raise their hands, however Litten jumps ahead to confront Incineroar. Ash is close behind to return his Pokémon. Team Rocket almost give away their host disguises and are frustrated by Ash's presence. Litten smells the Masked Royal and instantly recognises him, to which the Masked Royal smiles back and offers Ash and Litten a position in the first round. The Masked Royal asks if Ash has brought friends with him, and with that Kiawe alongside Marowak and Sophocles with Charjabug also enter the match up.
Meowth reminds the audience of the Battle Royal's ground rules, before the bell rings and the match begins. Litten makes the first move with Scratch, Marowak uses Bonemerang and Charjabug strikes with Discharge. Though the three attacks prove useless against Incineroar, who knocks Litten into Kiawe and Sophocles' Pokemon. Marowak goes in for a Shadow Bone, but the attack is deflected and Incineroar knocks Marowak on the head. Unlike the other two, Litten manages to withstand Incineroar’s Darkest Lariat. Ash is quickly reminded by Litten’s snarling and determination that the Battle Royal is a real match as the crowd start cheering for it. Incineroar uses Bulk Up to make itself bigger before grabbing Litten who was attempting a Fire Fang. The Masked Royal believes Litten wanted to become stronger, hence why it was so determined to battle a tough opponent. Incineroar follows up with a Throat Chop, sending Litten flying across the arena and defeating it. Ash and his friends retire to the Dome's entry stairs while Litten remains frustrated at its loss. Team Rocket watch on, and note that Litten could learn from them about coping with a loss. While Meowth is more sympathetic towards Litten, hoping it can win some other time.
At night, Professor Kukui and Ash observe Litten practicing on the beach. Kukui notes that Litten's wild side may have been activated by seeing its final evolution in action. Ash, Rotom, Lycanroc and Pikachu join Litten to help it train for another match against Incineroar. Ash observes Lycanroc and Litten's tail movement, similar to those seen when Lycanroc was still a Rockruff. Rotom suggests the movement may be a sign that Litten is about to learn Flame Charge; a move that increases a Pokémon's speed stat. Ash announces it is time for some special training, and has Litten over several days improve its agility and speed through various exercises like sparring with Lycanroc to master Flame Charge. Ash and his friends watch on in anticipation, however Litten still cannot use Flame Charge. Suddenly the Masked Royal and his Incineroar arrive on the scene, and are met with surprise and fanfare. The Masked Royal challenges Ash and Litten to a match, and they accept.
Litten's Fire Fang is counteracted by Incineroar’s Throat Chop, knocking it away. Litten gets back up and fires an Ember attack, though it is blocked by Incineroar's fire belt. Incineroar rushes in with a Cross Chop and Litten goes in with an underdeveloped Flame Charge before being hit back again. Ash commands Litten to use Flame Charge once more. This time, the flame surrounds its whole body. Incineroar catches Litten, though with Ash's encouragement it breaks free in a ball of fire. It lands on the ground, and amongst the flames Litten evolves into Torracat. With a new twist in the match, the Masked Royal is fired up and calls for a Darkest Lariat. Torracat has perfected its Flame Charge, and the attack proves powerful enough to stop Incineroar's move. Torracat tries another Flame Charge and slips through Incineroar's claws before returning back to clash with another Darkest Lariat. Both Pokemon are sent backwards, with Incineroar showing signs of exhaustion. And for the final clash, after bulking up, Incineroar uses its Throat Chop against Torracat’s Flame Charge. While Incineroar emerges victorious, Ash congratulates his newly evolved Pokémon for its efforts. The Masked Royal announces that Torracat and his Incineroar are now rivals and looks forward to another match at the Battle Royal Dome before performing his signature pose.
Overnight, Burnet wishes she could meet the Masked Royal, and asks Kukui if he would like to meet him. Though Kukui awkwardly laughs at the idea, while Torracat glares at him strangely.