Our heroes finally make it to Daybreak Town for Dawn's next Pokémon Contest, where they suddenly come across a Plusle and Minun who happen to belong with one of Dawn's rivals, Ursula. The two cute Pokémon scare Dawn half to death, which perplexes the rest of our heroes. Dawn explains that when she was in kindergarten, she was part of a team responsible for taking care of the class Plusle and Minun. Once, they zapped her for chasing them around and then holding them a bit too tight, making her hair stand on end and sparkle, prompting the nickname "Dee Dee Dancer," or "Dee Dee" for short. Ursula overhears this story and taunts Dawn with it, vowing to beat her in the Daybreak Contest.
Since it's a Double Performance, all Coordinators use two Pokémon. Dawn's Piplup and Buneary prove masterful, sending Dawn on to the second round, along with Jessilina (Jessie in disguise) and Ursula. Ursula assures Dawn she'll beat her in the upcoming round. But Dawn, with renewed confidence after her successful performance, has other ideas in mind!
The day before the Daybreak Contest will take place, the group arrives in town. Dawn and her Pokémon are enthusiastic to win their fifth Ribbon, so they all head towards the Contest Hall to practice. Ash comments that Dawn must want to work on her "Flame Ice" combination right up until the main event, but Brock warns that she can't just depend on "Flame Ice" and needs to rehearse other Appeals as well. As they finally reach the Contest Hall where other Coordinators are practicing, Dawn assures him that she's well aware of that, and is confident that they will win the Contest. Her mood suddenly plummets, however, when she spots a Coordinator's Plusle and Minun. Her face goes pale and she slumps to the ground, loudly proclaiming her displeasure as Ash and Brock look on in confusion.
Just as Ash is asking Dawn what's wrong, rival Ursula makes it known that the two Cheering Pokémon are hers. Noting that Dawn must be taking part in the Daybreak Contest as well, Ursula asks how many Ribbons she has earned. Dawn answers that she has four, but Ursula isn't particularly impressed; she, too, has four Ribbons, meaning that both of them are competing for their fifth. Dawn isn't worried, though, and asserts that she's been trying hard for the sake of her Pokémon, who happily give a cheer. Ursula still isn't impressed as she claims that she is the more amazing one - she has her trump cards specially raised for double performances, Plusle and Minun. As the two Electric-types jump out with their electric pom-poms, Dawn once again goes pale and falls to the ground. Ash reasons that it can't be the first time she's seen the Pokémon, and pulls out his Pokédex to look them up. Despite the Pokédex's claim that Plusle and Minun boost vitality, Dawn still wants nothing to do with them, and stretches out her arms to keep them away. Ursula is insulted by the gesture and decides to have the Cheering duo perform their Contest routine. Dawn shudders as they dance on either side of her, producing static electricity between them. With a sudden explosion, Dawn's hair is standing on end, glittering with sparks. Ursula finds this effect funny, and Brock leans over to let Dawn know that her hair is sparkling like a diamond. In shock, Dawn mutters under her breath about the glitteriness "D-Diamond?!"* before blacking out and collapsing backwards, to the surprise of all present.
Meanwhile, Team Rocket is hiding in the bushes, with Jessie dressed in her Jessilina costume. Meowth recognizes Ursula as the Coordinator who used a Gabite in the Chocovine Town Contest, and James notes that she's picking a fight with Dawn. Jessie, however, doesn't care to give her opponents any thought - she has no intention to lose either way. Meowth agrees that Jessie's victory is guaranteed, and James adds that his Carnivine will be performing its most ultimate Appeal. After the trio takes a moment to appreciate the days of suffering the Bug Catcher Pokémon went through for the sake of practice, Jessie assures them of certain victory, and the three put their hands in the middle to share a team cheer.
Back at the Pokémon Center, Ash and Brock watch over Dawn, who still hasn't woken up. Piplup shakes her arm worriedly before Dawn's eyes finally open and she jolts into a sitting position. As she gives a sigh, Brock asks if she's all right, and Ash offers her a mug of warm milk, which she accepts after putting her hat back on. Ash asks Dawn what happened, with Brock adding that it's strange to be so scared of Plusle and Minun. Dawn agrees that it's strange, her face falling. Brock asks if something happened to her in the past, from which Ash reasons that she must have failed at capturing a Plusle and Minun at some point. Dawn insists that this isn't the reason, but is reluctant to explain. Though Brock tells her that she doesn't have to talk about if she doesn't want to, Dawn explains that she had been planning to tell at some point.
Dawn reveals that it all occurred while she was in kindergarten. She, Kenny, and Leona had been put in charge of taking care of the Plusle and Minun at their school - feeding them, changing their water, and cleaning their living area. One day, however, Dawn was chasing after the two Pokémon while Kenny and Leona were diligently attending to their duties. Her two childhood friends quickly got irritated by her fooling around, and order her to do her job. Dawn, finally catching Plusle and Minun in her arms, insists that she is helping, by keeping hold of them so that they don't get in the way of changing their food and cleaning. The Cheering Pokémon in her arms yell out in protest and struggle to get free. Kenny realizes that the Pokémon don't like being handled in such a way, but Dawn insists that there's nothing to worry about - she's great friends with Plusle and Minun. She hugs them closer to prove her point, and the two Pokémon, finally reaching their limit, unleash an Electric attack to get her to let go. The attack works, and as Plusle and Minun scamper off, Dawn looks completely stunned, her hair sticking out on end and glittering. Kenny points out that Dawn's hair is sparkling like a diamond, Leona adds that it reminds her of dandruff (ピカピカしている). Building off both his and Leona's words, Kenny declares that he's going to call her Diamond Dandruff from that day on or Dee Dee for short. The awful nickname soon stuck after Kenny shouted it out in front of the whole class, leaving Dawn humiliated.
Dawn instantly gets mad at the boys for laughing, but Ash insists that it's funny, as Piplup continues to laugh especially hard. Brock clears his throat then and explains that Pokémon never attack without reason. Ash agrees, pointing out that it was because Dawn had been chasing after Plusle and Minun. Though shocked that it was her fault, Dawn realizes that it must be true, and looks upset. As Ash and Brock offer their reassurances, Dawn gloomily agrees, and Ash encourages her to beat Ursula in the Contest the next day, in order to overcome the past. A bit taken aback, Dawn says that it's a bit much, but assures them that there's no need to worry. Across the room, however, Ursula has been listening in, and seems quite pleased with what she's heard as she laughs to herself.
The following day, Marian welcomes everyone to the Daybreak Contest. Backstage, Ursula does her level best to unnerve Dawn before her performance, by having Plusle and Minun approach her as well as referring to her as Dee Dee. Dawn stands her ground, while Jessilina watches on confident the infighting will give her a chance at victory. Up first, Jessilina and Carnivine step onto the stage performing a synchronized arm-waving dance. Marian interjects, admitting that Jessilina needs two Pokémon for the Double Performance event. Jessilina asks her to be patient, before playing a flute to summon Seviper from its Poké Ball inside Carnivine’s mouth and onto the stage. Seviper then curls up and spins into the air, which transforms Carnivine’s Bullet Seed into green sparkles. For their finish, Seviper curls itself around Jessie while she strikes a pose and Carnivine provides an added Bullet Seed sparkle.
Later, Dawn calls Piplup and Buneary into the spotlight with a set of Star Seals. Buneary uses Ice Beam to suspend Piplup’s Bubble Beam in ice before Bouncing among them for an adorable Appeal. Dawn then has Buneary and Piplup spin to burst the frozen bubbles for a glittery effect, which goes over well with the judges. Next, Ursula has Gabite and Jigglypuff take the stage. Jigglypuff speeds into a Rollout while Gabite directs it with prowess. Gabite then tosses Jigglypuff high into the air with a flick of Iron Tail. It follows up with Stone Edge, which Jigglypuff destroys with Hyper Voice for a glittering effect. Jigglypuff then approaches with Gyro Ball, creating a brilliant glow as it collides with Gabite's Sand Tomb. Ursula has Gabite balance Jigglypuff on its claw for a perfect finish.
Afterwards, Marian announces the Coordinators moving onto the Battle Rounds, with Dawn, Ursula and Jessilina all advancing. Ursula reminds Dawn that she still has to face her Plusle and Minun if she wants to win her fifth Ribbon. Dawn remains confident in her abilities, but shrieks in fear when Plusle and Minun leap out of nowhere.