As Ash and his friends travel to Castelia City, site of Ash’s third Unova region Gym Battle challenge, they come across the grand opening of a huge new Poké Mart. It’s as big as a shopping mall!
Inside, they find a shop where a Pokémon Connoisseur is checking the compatibility between Trainers and Pokémon. Ash lines up to be evaluated as well, but just as he’s getting impatient with the wait, another shopkeeper invites him over. The proprietor is a girl named Burgundy, who insists that she’s a Connoisseur, too. But Ash gets suspicious when Burgundy says he should get rid of all his Pokémon because he isn’t compatible with any of them—even his best buddy Pikachu!
We then discover that she went up against Cilan at the Striaton Gym—and since her defeat there, she’s been holding a serious grudge. So, she studied to become a Connoisseur, then returned to challenge Cilan again. But by the time she got back, Cilan was already on his journey with Ash and Iris!
Burgundy challenges Cilan to a revenge battle, saying that if she wins, Ash has to give up all of his Pokémon. Ash is very worried, but Cilan accepts anyway, and in the process of defeating Burgundy, gently attempts to teach her the value of open-mindedness when evaluating Pokémon and Trainer compatibility. Angrily, she vows to come back again to beat Cilan, then stomps away. Ash is just happy that he can keep all his Pokémon, and they can again set their sights on the Castelia City Gym!
On their way to Castelia City, Ash and his friends run into a newly-opened Poké Mart. Excited, Iris runs in, followed by Ash and Cilan. In the market, Iris looks around at all the goods on offer, when a sales assistant offers her a Dragon Gem, a rare item that increases the power of Dragon moves by 50 percent. However, Iris decides that the item might be too early for Axew, and she passes on it, smiling.
Behind Iris, Ash spots a line of Trainers at a stall. Ash becomes puzzled, and Cilan explains that it is a Pokémon Connoisseur shop, which offers Trainers an insight into their friendship level with their Pokémon. Cilan adds that he is an A-class Connoisseur, and only A and S classes can provide appraisals. Ash is surprised to see that the Connoisseur is a woman, to which Cilan then informs him that female Connoisseurs are known as "Connaisseuses". Ash becomes excited and joins the queue to get his Pokémon checked by the Connaisseuse. He sees how long the line is and becomes dismayed. However, behind Ash, another Connoisseur calls for him behind a curtain.
When Ash approaches the curtain, the Connaisseuse forcibly brings him into her booth. The Connaisseuse introduces herself as Burgundy, and tells Ash that she could check the happiness of his Pokémon. She tries to start with Ash's Pikachu, but Ash politely refuses with a smile, telling her that he's certain that the bond between him and his Pikachu is strong. Burgundy then tells Ash that she'll check his other Pokémon, if that is the case. Ash brings out his Sewaddle, which Burgundy takes numerous pictures of it with her Pokédex. Burgundy is highly opposed to Ash's Sewaddle and furiously informs Ash that his Sewaddle's Ability is Swarm, and that he should switch it for a Sewaddle with Chlorophyll as its Ability. Ash presses her for an explanation, but she remarks that he shouldn’t argue with an expert Connaisseuse. Sewaddle becomes annoyed and responds by hitting Burgundy in the face with its String Shot. Burgundy becomes furious, and demands to see a different Pokémon of his. Ash declines, but calls out Snivy when threatened. Burgundy indicates that Snivy somehow has a 'bitter' taste to it and has the aroma of "black pepper." She actually tries to "taste" Ash's Snivy, though Snivy uses her Vine Whip attack, lashing Burgundy's tongue. Ash then brings out Tepig. Tepig smiles at Burgundy, which she observes with distaste. Then, she says that Ash's Tepig smiles too much and how that it doesn't really look like it's suited for battle. Tepig, much like Snivy, responds by letting its Ember loose and "roasting" Burgundy's head. Then, Oshawott suddenly pops out of his Poké Ball and tries to butter up Burgundy by hugging one of her legs and smiling cutely. Burgundy sees through Oshawott’s flattery and comments on his musky aroma. Oshawott then replies with a Water Gun that hits Burgundy square in the face. Then, Ash sends out his Scraggy. Burgundy states that Scraggy smells like an old shoe, and when Scraggy pulls his "pants" up, she tells him he should be ashamed of himself, and Scraggy Headbutts her. Finally, Burgundy takes a look at Ash's Pikachu, saying he wasn't as cute as pictures she had seen before, and Pikachu responds with Thunderbolt. Burgundy says that all of Ash's Pokémon are horrible and recommends he gets rid of all of them and get new ones, and Ash begins to argue with her. She shouts at him that he will never make it in the Unova League, with her bluntness taking Ash aback.
Suddenly, Cilan and Iris pull the curtains back to check up on Ash. Burgundy turns around, and as soon as she sees Cilan, she screams and points at him. Ash is confused, but Cilan explains that Burgundy challenged him a while ago, and lost. Burgundy then states that she has been waiting for this day, proclaiming it as her revenge day. Cilan asks why she wants revenge. Burgundy answers that she wants revenge on Cilan, not only because he had defeated her, but also for the hurtful comments he said about her Pokémon. She then conjures up an evil image of Cilan and his Pansage, laughing and mocking her. Cilan replies that he had never actually did these things to Burgundy. However, Burgundy continues, revealing that she attended the Pokémon Connoisseur Association and earned herself accreditation after undertaking an exam. She returned to the Striaton Gym for the planned revenge, but Cilan had already left on his journey with Ash and Iris, much to Burgundy's total dismay. Cilan apologizes to her, but explains that he cannot have an official Gym battle outside of a Gym. Burgundy rubbishes his excuses, and reveal that she earned the Trio Badge after defeating Chili.
Burgundy proclaims that she dreams of opening her own Connaisseuse shop, to which Cilan asks about her class; she admits that she is a C-class, and Cilan admits that means she is only a beginner and can only work as an assistant. Ash is furious upon hearing this, and questions her so-called expert opinion. Burgundy boldly proclaims any other Connoisseur would say the same thing, but Cilan thinks otherwise and questions Burgundy’s evaluation methods. Then, Burgundy challenges Cilan to a Pokémon battle to prove her skills. They step outside, and agree to a two-on-two match. Burgundy brings out Dewott and Cilan selects his Dwebble. Burgundy gives her evaluation and mocks Cilan, seeing that he has picked a Bug-type and Rock-type, which is weak to her Water-type. Burgundy wants to have the battle with a special condition: if she wins the battle, Ash will have to change all of his Pokémon with different ones. Cilan agrees without a moment of hesitation, much to Ash's shock.
Burgundy immediately commands Dewott to use Fury Cutter, though it fails to do any damage against Dwebble and its Protective shell. Burgundy then commands Dewott to use Water Pulse, which hits Dwebble squarely. Burgundy is convinced Dwebble will faint, but is speechless when it makes a recovery. Cilan explains that Dwebble's Ability is Sturdy, and how it cannot be KO'd by one move. Then, Cilan orders Dwebble to use Shell Smash. Dewott also leaps into the air and uses Razor Shell. Quickened by the move Shell Smash, Dwebble blocks off the move with its X-Scissor. Both Pokémon seem to have received a glancing blow, but it's obvious that it was too much for Dewott. It staggers, drops back down to the ground, and faints. Burgundy can't understand why she had lost against a type that was weak against her Pokémon. Cilan replies, telling Burgundy that Pokémon battling isn't all from the manual. His strategy was to focus on Dwebble's Ability and its powerful defenses, and then attack Dewott when it was weak from attacking Dwebble.
Burgundy sends out her "premium-brand" Sawsbuck, to which Cilan offers his evaluation that she still needs time to perfect her strategy. Cilan sends out Pansage, his "premium-brand" Pokémon. Burgundy orders Sawsbuck to use Horn Leech, which Pansage dodges with ease. Burgundy then orders Sawsbuck to use Megahorn. Cilan commands Pansage to use Dig, allowing it to avoid Sawsbuck's Megahorn and he soon resurfaces to land Bullet Seed on Sawsbuck. Cilan smirks and commands Pansage to finish it off with Solar Beam. Pansage uses Solar Beam, lighting the whole field. Sawsbuck then passes out and topples to the ground, ending the battle with Cilan's victory. Burgundy calls her Sawsbuck back to its Poké Ball.
With the sun setting, Cilan offers Burgundy some useful advice, however she becomes agitated by yet another lecture. Burgundy replies with dislike and swears that she become an S-class Connaisseuse. With a kind smile, Cilan replies by wishes her all the best, which takes her by surprise. Burgundy rushes off, determined to beat Cilan next time. Afterwards, Cilan admits that the C-class exam isn’t an easy task and gives Burgundy some credit for her spark. Ash returns his attraction to his upcoming Castelia Gym challenge.