After successfully clearing the second round of the Gloire City Pokémon Showcase Master Class, Serena, Shauna, and Jessilee are ready to face off in the semifinals for the right to challenge Aria. The title of Kalos Queen is two victories away and all three Performers are determined to take it from Aria. Monsieur Pierre reminds the audience that contestants in the semifinals must perform together with two Pokémon and announces the start of the round, revealing that Jessilee will be the first one to perform.
For her performance in the semifinals, Jessilee has decided to use her Gourgeist and Meowth. She starts by telling Gourgeist to use Seed Bomb, which creates gigantic roots that lift Jessilee up in the air. She then commands Gourgeist to use Seed Bomb again and this time the seeds explode, creating a fireworks display. To finish, she asks Meowth to use Fury Swipes to destroy the giant roots, which results in sparkles falling down on them as they pose together. On Shauna's turn, she asks Ivysaur to use Vine Whip to move her around the stage while Flabébé uses Fairy Wind to leave a trail of pink dust behind Shauna. Then she commands Ivysaur to use Vine Whip to make a tornado out of the Fairy Wind, sending Shauna upwards. Shauna finishes her performance by having Flabébé using Moonblast while Ivysaur uses Solar Beam. The two moves collide and sparkles are sent down on them.
With the end of Shauna's performance, Monsieur Pierre welcomes Serena to the center of the stage. She begins by commanding Sylveon to use Swift, which is followed by Pancham's Stone Edge. Sylveon jumps over the pillars of rock and uses Fairy Wind from above, creating a tornado that lifts Serena and Pancham up in the air. The three of them pose in mid-air before landing, and while Pancham lands on his paw and Sylveon on her ribbon-like feelers without a hitch, Serena ends up hurting her hand. She loses her balance and is about to fall, but Sylveon manages to catch her using her feelers, safely placing her on stage. Palermo and Aria take notice of Serena's mistake, but the audience is excited with her performance. After that, Pierre asks the crowd to vote using the Glow Caster. He adds that people watching on television may cast their vote using their devices and pressing the button that corresponds to their favorite Performer. The voting ends and Pierre announces that Serena will be the one challenging the reigning Kalos Queen Aria in the final round.
As Serena cries tears of happiness and thanks her Pokémon, her friends celebrate and Grace raises from her seat and tells everyone that Serena is her daughter and that she is very proud of her. Meowth and Gourgeist are afraid of Jessie's reaction, but she is happy to have made it this far and says that Kalosians now know what a beauty she is. Shauna goes to congratulate Serena and starts crying. Although she is upset that she lost, she asks Serena to do her very best in the finals for the sake of every Performer in the Master Class. After that, Serena heads to a waiting room, where she removes her glove to reveal a wrist sprain. Palermo appears and asks to see Serena's wrist. Serena is surprised that Palermo knows about her injury and Palermo tells her to forfeit the finals as she will not be able to put on a proper performance. Serena says that becoming Kalos Queen is her big dream and she will not stop until her chances are over. This reminds Palermo of a similar occurrence that took place during one of Aria's practice sessions back when Palermo used to tutor her. Palermo then applies a bandage to her wrist, saying that she can make it hold for one performance and asking Serena to go see a doctor afterwards.
On stage, Pierre announces that the title of Kalos Queen is up for grabs and that Performers may use as many Pokémon as they want in the finals. He then introduces the challenger, Serena, and the current title holder, Aria. Aria stares at Serena, thinking that there is no need to hold back against someone that is as determined to win as Serena is. As the challenger, Serena has to perform first, and she is going to do so with all three of her Pokémon. Their performance starts with Braixen using Flamethrower and Pancham using Dark Pulse, and just as the two moves collide Sylveon hits them with Swift. Then Braixen uses her branch to start a ring of fire before tossing the branch to Serena so she can complete the ring. They all dance in the middle of the ring and Pancham uses Stone Edge. Sylveon jumps over the rock pillars and uses Fairy Wind, sending her Trainer and her teammates upward. Then Pancham, Sylveon, and Braixen use Dark Pulse, Swift, and Flamethrower to create an enormous flower, which explodes and showers them with sparkles that mark the end of the performance.
Aria comes next to defend her title. She starts by having Delphox use Mystical Fire upwards as Vivillon flies and uses Psybeam downwards so the two moves can collide in mid-air. Then she asks Aromatisse to use Reflect, creating multiple translucid circular platforms which Aria uses to jump as Vivillon catches her in the air and lifts her up. The audience members are very impressed and they rise up from their seats. Across Kalos, people on the streets stop for a moment to see Aria performing. She finishes with Delphox using Fire Blast, which explodes into sparkles that fall on them as they smile and strike an elegant pose. After that, Pierre asks everyone to cast their votes, wanting to know if a new Kalos Queen will be crowned or if Aria will hold on to her current status. The voting ends and Pierre announces that Aria has successfully defended her crown. Up in the audience, Bonnie is sad that Serena lost, but Clemont thinks that Serena's performance was great and Ash says that Serena still has her dream to hold onto.
Monsieur Pierre asks Klefki to bring Aria her tiara. After being crowned, Aria goes on to talk to Serena, saying it was fun to stand on stage with her and that she wants to perform with Serena again sometime. Serena agrees and says that she will continue working hard and soon enough she will become Kalos Queen. Aria and Serena wave to the audience as Pierre brings the Gloire City Pokémon Showcase Master Class to a close. Backstage, a doctor is seen bandaging Serena's wrist and telling her to take care. Palermo appears right after and asks Serena how she feels, telling her to never push herself like that again, especially if she wants to defeat Aria. Grace appears by the door and overhears their conversation as Serena's mind goes back to when Palermo told her that she was lacking something crucial to become Kalos Queen and without knowing what that something is, she could never defeat Aria.
Serena reveals that watching Aria's performance made her realize what she is lacking. She says that she has a lot to learn and that her friends and Pokémon are always supporting her while Aria makes people smile and gives them strength and advice, concluding that Aria is a giving person while she has been on the receiving end all this time. She says that she wants to become Kalos Queen so she can start giving back too and that she will work hard to achieve that goal. Palermo says that now that Serena has realized that, she will become an even better Performer. She asks Serena if she would like to learn everything about being a Performer with her. Serena is taken aback by this and Palermo says she should give it some thought and answer later. Palermo leaves the room, encountering Grace at the door.
Outside Gloire City's castle, Serena and her rivals say their goodbyes. James, Meowth, Gourgeist, and Inkay are all dreading Jessie's reaction to the end of the Master Class, but she thanks them and says that she would not have made it to the semifinals without their help. At the Pokémon Center, Serena tells her mom that she tried to win, but came up a bit short. Grace says that what matters is that Serena did her very best and tells her to move on to her next goal. Grace then heads back to Vaniville Town. At night, Serena is sitting outside with her Pokémon as Ash appears and asks if her wrist hurts. She says that she is just sitting there thinking and Ash assumes she is planning her next performance. He says that whenever he loses a battle, he starts to think about the strategies he is going to use in his next challenge. Serena is impressed by Ash's optimism and says that it all seems to come so naturally for him, to which Ash replies that he does not always knows what to do, but he would rather do something even if he fails, as nothing he does in his journey is a waste of time. The next day, Serena goes to talk with Palermo. She says she is happy that Palermo has offered to tutor her, but she cannot go with her at the moment as she wants to keep traveling with Ash and the others. Palermo hands Serena a business card and tells her to give her a call when she feels she is ready for the next step. After that, the group leaves Gloire City for Snowbelle City, where Ash plans to earn his eight Gym Badge.