Ash and Goh return to Cerise Park from a trip to Unova, with Goh presenting his Pokémon with their newest playmate: Lilligant. The Pokémon of Cerise Park find Lilligant's sweet aroma very soothing and charming, but none more so than Heracross. When Pinsir comes to bring Heracross a flower wreath it has made for him, it's distraught to see its beloved being in love with someone else. Goh soon notices Pinsir's depression, and after witnessing Heracross being smitten by the scent of Lilligant's flower, he realizes that Pinsir must been distraught over Lilligant "stealing" Heracross's love from it.
While thinking of a solution for Pinsir's problem, Ash and Goh overhear Chloe telling Professor Cerise about a Pokémon flower arranging class she and Eevee are planning to attend in order to meet a Leafeon. Goh latches onto the idea that learning about flowers could help Pinsir win over Heracross again and decides to attend as well. Chloe is initially confused, but an explanation during the bus ride to Celadon City makes her understand the situation.
Ash, Goh, and Chloe arrive at the Celadon Gym, where they sign up for the class and are greeted by Gym Leader Erika, who recognizes Ash as the person who saved her Pokémon back when the Gym caught fire. She tells Chloe that the Celadon Gym researches aromas emitted by flowers and Pokémon, such as her Leafeon, and makes perfumes out of them. As per usual, Eevee eagerly mimics her evolved form's movements, with Chloe explaining to Erika that her Eevee is unsure what she wants to evolve into, so they're trying to get as much experiences as they can. Moving over to the Gym's greenhouse, Erika explains to the group the concept of Pokémon flower arranging, which uses decorating Pokémon with flowers as a way to express the bond between them and their Trainers, with her decorating her Leafeon as an example. Erika's attention is drawn to Goh when he mentions he wishes to use the flowers to make his Pokémon fall in love with each other. At first, Goh thinks Erika is judging him over this, but instead, she finds the idea lovely and offers to support it in any way she can.
Outside the glass wall of the greenhouse, Team Rocket is plotting to make yet another attempt to steal Pikachu. As such, they infiltrate the class in disguise, looking for a chance to snatch Pikachu unnoticed while pretending to decorate Meowth and Wobbuffet. When Erika recommends everyone to come up with performances that'll make use of their Pokémon's characteristics, Ash gets the idea to use a box filled with Christmas decorations to his advantage, while Goh comes up with an idea involving Grookey. When the time to present the finished works arrives, Team Rocket sneaks outside under the pretense of going to pick some flowers. Since Pikachu stuck too close to Ash to be snatched without being noticed, they decide to grab the Mouse Pokémon by force and call down the Rocket Prize Master, which gives them a Lurantis and a Leavanny.
Back inside, Chloe, Ash, and Goh each present their Pokémon in turns. Eevee is decorated with the same kinds of flowers Erika had decorated her own Leafeon with earlier; Pikachu is decorated with Christmas lights that he powers up with a Thunderbolt; and Pinsir has donned a flowery dress and decorations, with Grookey using its powers to make the buds in the costume bloom and thus make it even more beautiful. Goh reveals that he brought Heracross along too so he could see Pinsir with its flower decorations. However, just as he calls Heracross out, Team Rocket snatches Pikachu with Leavanny's String Shot and takes off their disguises, causing everyone's attention to focus on them. James tells Leavanny to use String Shot again to catch more Pokémon, but Erika has Leafeon use Razor Leaf to cut the strings before they reach anyone, while Pikachu frees himself with Iron Tail and joins the battle.
While Lurantis and Heracross exchange blows, Eevee uses Copycat to mimic Leafeon's Razor Leaf, which, combined with Pikachu's Thunderbolt, is enough to defeat Leavanny. Lurantis pushes Heracross back with Petal Blizzard, before charging up a Solar Beam. Seeing its beloved is in trouble, Pinsir jumps in front of the Solar Beam just as it's fired, taking the hit for Heracross. Goh has Pinsir use X-Scissor, which sends Lurantis flying into Team Rocket and causes them to blast off again. While Pinsir's flower costume was destroyed by the Solar Beam, the bravery Pinsir just showed was enough for it to win back Heracross's love.
As the group prepares to leave, Erika gives Chloe a bottle of Leafeon perfume, and Pinsir, flustered by Heracross trying to hold its hand, suddenly grabs him with its pincers as a form of hug, causing both Heracross and Goh to panic in surprise.