Gardenia and Cherubi are enjoying the scents of Eterna City, when she suddenly begins to smell gas. Gardenia realizes that the scent is coming from Diamond, Pearl, and Platinum and rushes toward them. The three don't acknowledge her presence, offending her. When Diamond and Pearl walk away from her, she calls on her Roserade to use Grass Knot to trip them.
Gardenia asks them if they recently fought a Gas Pokémon and Diamond confirms her suspicions. She asks them where the battle took place, and is horrified to learn it was in the Old Chateau. Gardenia reveals that she has always wanted to investigate the building, and through fearful shuddering, denies that the reason she put it off was because she was too scared to visit. She is impressed by Diamond's success in defeating a ghost, and proudly reveals to the group that she is Eterna City's Gym Leader. She assumes that Diamond would like to battle her and agrees to a challenge he never asks for. Pearl suggests to Platinum that she now has an appointment for a Gym battle.
At the Eterna Grand Hotel, Diamond and Pearl practice their comedy routine as Platinum trains outside. Platinum contemplates her adventure so far, happy that she is finally able to apply her knowledge while experiencing the world around her. She makes a plan with Piplup to battle every Gym Leader she encounters.
When Diamond and Pearl see Platinum's determination to train hard, they decide to help out by making a paper mask of Gardenia's face and challenging her outside. Pearl deduces that Gardenia specializes in Grass-type Pokémon and decides to have Platinum practice in a grass field. Walking past a massive bronze statue of a Pokémon, they find a grassy spot in front of a building with large spikes protruding from its walls.
Diamond and Pearl have Tru and Chimler battle against Piplup at the same time. Platinum is able to defeat Chimler, but struggles against Tru, causing Pearl to call for a break. Shortly after the battle, Platinum hears a quiet call for help. She asks the others if they hear it too, but neither of them know what she is talking about.
As the three continue practicing, they catch the attention of a woman who happens to be walking by. She chuckles as she watches them battle, then notices all three of their Pokémon are about to evolve. Just as she predicts, Tru, Chimler, and Piplup evolve into their second forms.