Ash and his friends have reached Shelter Town, a snow-covered town near Snowpoint City, and they’re taking a break at the Pokémon Center. When Dawn brings out her Buneary, it attracts attention from Marilyn, a Trainer who loves cute Pokémon more than anything else. Marilyn thinks Piplup isn’t cute at all, but she wants to battle Buneary; Dawn agrees, eager to avenge Piplup’s pride. As it turns out, Marilyn only wants to watch her Cherubi act dramatic. Brock has to prod her to actually battle, but when she does battle, she wins!
To show Marilyn that cuteness isn’t everything, Brock asks her for a battle. She doesn’t like his Sudowoodo or Croagunk, but she agrees to a 3-on-3 battle if it includes Brock’s super-cute Happiny. Team Rocket wants to get their hands on Marilyn’s adorable Pokémon, so James disguises himself as the match referee. The match begins with Sudowoodo battling Cherubi, and Sudowoodo uses Mimic and Fake Tears to imitate Cherubi’s acting. Marilyn has to admit, Sudowoodo’s dramatics are as good as Cherubi’s—but James wants to see Marilyn’s other Pokémon, so he calls it a tie and calls for the next set of Pokémon!
Now it’s Croagunk vs. Marilyn’s Chingling. Chingling has the upper hand, but Brock shows Marilyn how a Trainer’s encouragement can inspire a Pokémon to keep fighting. So when it’s time for Marilyn’s third Pokémon, she changes her team and sends out a Shellder! She always thought Shellder was cute, but people teased her and soon she became obsessed with typical “cute” Pokémon. Now she’s ready to stand behind her Shellder! But before Shellder and Happiny can battle, Team Rocket steals her Cherubi and Chingling. Shellder promptly freezes Team Rocket so Marilyn can rescue her Pokémon, and Happiny blasts Team Rocket into the sky. Brock’s lesson worked: Marilyn is proud of her Shellder again, so our heroes can change into cold-weather gear and get ready to leave for Snowpoint City!
Ash and his friends emerge from the tunnel and receive a very cold welcoming, having now entered the snowy north of Sinnoh. Just ahead is Shelter Town, the final stop before Snowpoint City, so the group makes a pit stop at the local Pokémon Center. There, Dawn asks after a package that is due to be delivered to her, however Nurse Joy informs her it hasn't arrived yet. To pass the time, Dawn lets Buneary out of her Poké Ball to let her have some fun with the other Pokémon. Cute Pokémon enthusiast Marilyn takes the group by surprise when she comes racing for Buneary and starts to hug her. She explains that her criteria for cuteness is that the Pokémon must be under 2 feet tall, must not have evolved, and looks "absolutely lovely". Therefore Dawn introduces her Piplup. Despite the fact that he meets two of her requirements, Marilyn discourages the fact he's cute and starts to remark on the features that turns off Piplup's cuteness, causing Piplup to be paralyzed in shock. After calling Dawn "Dawny", claiming it was a cuter name than Dawn, Marilyn asks Dawn for a battle, which she accepts.
Marilyn almost forgets about the battle when Buneary is called out. She apologizes before sending out her Cherubi onto the field. While Marilyn is too busy fawning over her own Pokémon, Buneary batters Cherubi around with Dizzy Punch. Dawn calls for an Ice Beam, and Marilyn replies with Protect, however Cherubi still recoils in pain even though Protect was successful. Brock realizes that this is simply Marilyn's attempt to stall the battle, and he orders her to battle properly or be disqualified. Marilyn changes her ditzy demeanour and orders Brock stay out of this, and proclaims that this match is an art form and will be the most valiant battle ever. Brock persists, so Marilyn complies, knocking Buneary out with a fury of attack before dealing the final blow with a Solar Beam. Marilyn is very pleased with herself, while Brock refuses to believe that a Pokémon's cuteness is their only asset in battle.
Nearby, Team Rocket plans on taking Marilyn's Cherubi by tricking her to battle them. After some thought, Jessie has James hand over Mime Jr. as it meets Marilyn's cuteness criteria. Jessie, disguised as cuteness aficionado Jessirilyn, confronts Marilyn and tells her she wants to battle and shows Mime Jr. to her, Marilyn however disagrees that it's cute crushing Mime Jr.'s feelings before walking off. James comforts his broken-hearted Pokémon before putting Team Rocket's next ploy into motion. Hoping to teach Marilyn the true value of every Pokémon, Brock challenges her to a three-on-three battle. Then James enters disguised as an official match referee offering his services and Marilyn, not realizing this is a little too convenient, asks him to officiate the battle.
After James announce the rules, Marilyn and Brock sends out Cherubi and Sudowoodo respectively. Sudowoodo starts with Double-Edge which scores a direct hit, making Cherubi fall down dramatically. Marilyn however ignores the fact it was hit and remarks that Cherubi took the hit valiantly, causing Brock to scold her some more. To beat Marilyn at her own cuteness game, Brock orders Sudowoodo to use Mimic, causing it to fall down dramatically too, followed by Fake Tears. This causes Marilyn to start realizing the true strength of Pokémon. Wanting to move things along so he can see what other Pokémon Marilyn has, James declares the round as a tie as the two Trainers recall their Pokémon to their Poké Balls.
Brock sends out Croagunk while Marilyn calls out Chingling. Croagunk gains the upper hand against Chingling. However Dawn sees through the act and orders Marilyn to get to the point, with Marilyn hastily obeying. She orders Chingling use Growl along with Confusion and Croagunk is almost knocked out. Brock isn't willing to give up and encourages Croagunk to get up, and not wanting to let Brock down it does and uses Brick Break, defeating Chingling. Brock tells Marilyn that any Pokémon can be valiant regardless of their looks, unless the Trainer bonds with their Pokémon. The two return their Pokémon, with Brock congratulating Croagunk on an excellent battle.
Having listened to Brock, Marilyn switches a Poké Ball containing a cute Pokémon for another Pokémon, which her friends mocked her for. Like Happiny, Marilyn's Shellder makes its battle debut. Meowth and Jessie are disturbed by the choice of Shellder, and rope down from the ceiling to confront Marilyn over it. James removes his disguise and riffles through Marilyn's bag to steal the Poké Balls containing Cherubi and Chingling. Marilyn deals with the troublesome trio swiftly, having her Shellder use Brine to catapult itself into them. The stolen Balls are flung out of the trio's grasp before Marilyn has Shellder freeze Team Rocket with an Ice Beam. Brock's Happiny uses Pound to send Team Rocket blasting off. Brock is glad to see that Marilyn has heeded their words, and is not so occupied with the cuteness factor of her Pokémon.
Later, Dawn receives the package from her mother, which contains winter clothing for her, Ash and Brock. Now dressed in thick jackets and boots to brave the cold, the group prepares to head towards Snowpoint City so Ash can battle for his seventh Sinnoh Gym Badge.