The day before the Dendemille Town Rookie Showcase, Serena beholds the view of Dendemille Town at night alongside her Braixen and Pancham, determined to win this time round. The following morning, Serena gives Grace a call, revealing that she intends to wear the dress she received from Valerie. The group proceeds to the arena where the showcase is to be held, encouraging Serena, when they hear a familiar voice. The voice is revealed to belong to Miette, who shows up with her Slurpuff and a male Meowstic. Teasing Serena over her new appearance and crush on Ash, Miette confirms that she intends to compete as well. Privately, Miette also whispers to Serena that she's still intent on having a chat with Ash, flustering Serena. Ash, oblivious to this, wishes both the girls luck. Bonnie remarks on Ash's cluelessness, and that of her brother as well as Clemont is equally confused. From behind the bushes, Jessie notices the group and declares that she's going to win the Showcase. James and Meowth agree that Jessie has been specially training for this occasion.
Inside, Monsieur Pierre begins proceedings as Ash, Clemont and Bonnie watch in the audience; at the same time, Grace, Shauna, Tierno, Trevor, Aria, Professor Sycamore and his assistants are revealed to be tuning in as well. Pierre reveals that the Showcase will begin with a Poké Puff bake-off, with only one out of three in each group of participants being allowed to proceed. Gena, Pokémon Connoisseur Santo and Showcase Expert Delilah will be judging. Miette is up first along with two other participants, and she wastes no time in using Slurpuff's superior senses to choose ingredients and Meowstic's Psychic to help in mixing. At the end of the round, the Poké Puffs are brought to the judges for Santo's Mime Jr., Gena's Jigglypuff and Delilah's Furfrou to sample; Miette is declared the winner. Ash and his friends are impressed at Miette's skill, while Serena silently watches backstage, equally awed.
Jessie, entering as "Jessilia", is next to compete, with Meowth and Wobbuffet as her assistants. Meowth confirms to Jessie that he investigated the judges' Pokémon to find out what flavors they liked, and all they would need to do is to bake a Poké Puff that appeals to all three. Meowth succeeds in baking several somewhat lumpy Poké Puffs, but before he can begin decorating Jessie abruptly takes over, much to Meowth and Wobbuffet's horror. Sure enough, Jessie's Poké Puffs end up slathered with a pyramid of cream with a mess of toppings scattered on top. Santo is perturbed at Jessie's design sense, but both Gena and Delilah point out how much the Pokémon are enjoying how Jessie's Poké Puffs taste, and declare Jessie as the winner. As Jessie gushes happily, Serena again marvels at how tough the competition is this time.
Finally, it's Serena's turn to compete. Trying to keep a cool head, Serena assigns Pancham to mixing and Braixen to baking, recalling all the practice they've been doing with baking Poké Puffs for the group's Pokémon. By the end of the round, the judges comment that all three participants have performed excellently, making for a difficult decision. Worried, Serena shuts her eyes tightly as the spotlights move across the stage, finally landing on her much to her surprise and joy. Ash and friends are happy for Serena as their Pokémon hungrily look on at Serena's creations. Miette is likewise pleased that Serena qualified, as are the others tuning in.
Moving onto the next segment, Pierre introduces Jessie as the first competitor for the Freestyle Performance round. James cheers loudly for her, drawing the gazes of the spectators around him. With Wobbuffet and Meowth dressed as clowns, Jessie begins by swinging Meowth around before tossing him into the air, and as he lands, Wobbuffet uses Counter to bounce Meowth up and down. Although initially confused, the audience soon warms up to this act. For a finale Jessie flings a collection of Berries upwards, which Meowth slices into pieces, forming a trio of heart-shaped trees as they land. The audience applauds this act loudly as Ash, his friends and Serena remark on the skilled performance demonstrated. Backstage, Serena proceeds to the stage, only for Jessie to bump into her, knocking her into some props. Jessie rudely dismisses Serena, much to the anger of her Pokémon, but Serena tells them to stand down and apologizes. Jessie haughtily leaves the scene, but before Serena can get up she notices that the collision tore her dress.
Miette is next to perform, and she has Meowstic lift Slurpuff into the air with Psychic as the latter uses Cotton Spore, casting a circle of sparkly dust over her. Clemont comments on Miette's showmanship, to which Bonnie quickly points out Serena's skill. As the other performances go on, Serena begins to worry about her torn dress, but eventually regains her courage as she remembers Ash's own determination. She quickly manages to mend her dress by trimming the hem, running onto the stage at the last minute to begin her performance. Ash and friends cheer for her, though they also note her modified outfit. Beginning with a dance with Pancham, Serena has Pancham use Dark Pulse to scatter purple sparkles around them as Braixen summons pillars of fire while she dances, surrounding the three of them with flames and sparkles. Pancham follows up with Stone Edge, which break apart into more sparkles as Braixen leaps onto them, and the two Pokémon finish with another collision of Dark Pulse and Flamethrower.
With the conclusion of the Showcase, Pierre requests that the audience vote for their favorite contestant. James is first to vote for Jessie, and the judges soon follow with their votes. Ash's group cheers for Serena as their votes join the others from the audience. Unable to help herself, Serena tightly shuts her eyes again, recalling the times when she challenged her mother to a race on Skiddo to pursue her dream, and when she suffered her first defeat at the Coumarine Showcase. Eventually, Serena opens her eyes to see a stream of votes pouring at her; Miette and Jessie are likewise surprised. With most of the votes in her favor, Pierre declares Serena to be the winner of the Dendemille Showcase, much to the joy of Serena and her Pokémon. All of her friends are just as happy and proud for her, with Shauna declaring that she's going to train hard in being a Performer as well. Pierre presents Serena with her first Princess Key.
Outside, the group congratulates Serena on her win, pointing out her costume. Serena explains what happened, wondering if she should apologize to Valerie for cutting up the dress she made. Ash comments that Serena looked amazing in it; sneaking from behind, Miette agrees as well, surprising Serena. Miette congratulates Serena but declares that she will win the next competition, and the two rival Performers shake hands. Leaning in, Miette reminds Serena she hasn't forgotten about their "other" competition, referring to Ash, once again flustering Serena as she bids the group farewell. The episode closes with Serena looking proudly at her first Princess Key.