Since the Gym in Opelucid City was closed, Ash had to use the Virbank City Gym as a substitute and here he meets the ultra-punky Roxie who has a Koffing (from Ash's home region in Kanto while they perform a rock concert). And introducing her band, "Koffing and the Toxics." He find out soon enough that the Virbank Gym doubles as a live venue. With a loud Thunderbolt from Pikachu to rock their socks off! Ash challenges the young Poison-type Gym Leader to a Poisonous Gym Battle in which she accepts with one condition: Ash will battle with a full team of six Pokémon while she uses only three Poison-type Pokémon. What Poison-type Pokémon strategy will this next generation Pretty Poison have up her sleeve? The Virbank Gym 6 on 3 battle begins now!
The heroes are heading over the Pokémon Center to get some rest. Ash remembers he needs to plan a strategy for his upcoming Gym Battle. Suddenly, a boy runs near them, so Cilan suspects he had a Gym Battle recently. Meanwhile, the Pokémon Ash rescued in PokéStar studios observes him. The heroes enter the Center and see the trainer with his Pokémon, poisoned. They speak with the boy, who talks about the Gym Leader, her speciality being Poison. They also hear other trainers, who also report their Pokémon were poisoned. The heroes see this is a serious difficulty. Ash thinks of his team to defeat the Gym, bearing in mind he needs an anti-poison team. He gets hungry, though, and runs off.
Team Rocket, on the other hand, report they encountered the Mythical Pokémon, but it vanished. Dr. Zager understands that and promises to send some goggles to allow them to detect the Pokémon. He logs out, while Team Rocket think that Pokémon lies in Virbank City. Next morning, Ash runs out, while Cilan and Iris order him to slow down. Cilan stops and sees the entrance to the Virbank Gym, a simple door. They come in, down the stairs and enter the Gym itself. They are suddenly overpowered by the sound of music, and see that the Gym Leader has just defeated another challenger and his Gothitelle. Cilan notices the Gym Leader's Koffing, stating that it's the first time he's seen one in person. The Gym Leader still congratulates on the challenger for this brave battle. The challenger is surprised, calls Gothitelle back and thanks her for the battle, then leaves.
The Gym Leader, Roxie, spots Ash, her new challenger. He greets her and Roxie sees Ash is from Kanto; she mentions that she met Koffing at a concert there. Cilan wonders what she means by concert, so Roxie replies they are a punk band known as "Koffing and the Toxics"; they also play music around as well. Iris and Cilan see that nobody can think of a strategy with all that noise, so Ash's Pikachu uses Thunderbolt, displaying power. Ash challenges Roxie to the Gym Battle, showing he needs a final badge to enter the Unova League. Roxie is impressed, but replies that she won't make it easy for him, though Ash replies it is worth the Gym Badge. Roxie proposes a 3-on-6 battle. Ash replies it is unfair he has to use six, while she uses three Pokémon. Roxie replies she needs to see how well he has trained and bonded with his Pokémon. Plus, he will thank her later for that opportunity.
Cilan and Iris feel that Roxie must have a lot of faith in her Pokémon, as this battle will require brains and tactics. The battle starts, and Roxie sends out Koffing and Ash his Boldore. The heroes are surprised that everyone is cheering for both Roxie and Ash. Boldore starts with Sandstorm, which deals considerable damage to Koffing, but it then uses Clear Smog to blow away Sandstorm. Boldore uses Rock Blast, but Koffing uses Gyro Ball to deflect the attack and hit Boldore. Koffing then uses Sludge Bomb, which clashes with Boldore's Flash Cannon. Koffing uses Gyro Ball again, and Boldore tries to slow it down with Sandstorm, but fails and gets hit and defeated. Ash admits Koffing is strong, but it only makes this Gym Battle interesting, making Roxie pleased by his thoughts. Ash recalls Boldore and sends out Unfezant.
Unfezant starts with Quick Attack, hitting Koffing. Koffing uses Will-O-Wisp, but Unfzant blows it away with Gust. She uses Air Cutter, but misses and gets poisoned by Sludge Bomb. Koffing then uses Clear Smog, affecting Unfezant. Concerned, Ash asks Unfezant if she can still battle, and Unfezant confirms. She uses Aerial Ace, but is countered by Koffing's Gyro Ball. Unfezant repeats the attack, but is once again countered and finally defeated. Ash calls Unfezant back, knowing it will be hard if they are struggling with Roxie's first Pokémon. He brings Leavanny, though Roxie reminds him that the Grass-type is vulnerable to poison. Leavanny uses Energy Ball, hitting Koffing, who uses Gyro Ball. However, Leavanny stops it using String Shot.
Koffing tries to use Sludge Bomb, though Leavanny spins it around, reels it in and uses Energy Ball to defeat Koffing. Cilan realizes Ash wanted to lower Koffing's Special Defense, then reel it in with String Shot, knowing the next move would defeat it. The Pokémon Ash saved before watches the battle and is glad Ash won. Roxie is amazed by Ash's strategy, but does not give up and raises the difficulty, sending out Scolipede. Leavanny uses Razor Leaf, but Scolipede is not affected by that move. It blasts Leavanny with Toxic, poisoning him.
- Who's That Pokémon?: Koffing (JA and EN)
- Like in "The Great Eight Fate!", Ash battles the Gym Leader, Juan, which is split into two episodes in a row. In addition, Ash had to fight both of them for the eighth and final badge.
- Roxie is the first Gym Leader who made her anime debut prior to the game she was in, Pokémon Black 2 and White 2.
- There was a moment similar to "Electric Shock Showdown" where trainers were being beaten one after another by Roxie.
- The effects of poison has the same visual as the effect of paralysis in the anime, only purple.
- This is the second time Koffing was featured in "Who's that Pokémon?" in the English version. The first time was way back in "Pokémon Emergency!"
- This episode marks the first time Ash faced a Gym Leader and used more Pokémon than they did since his rematch with Whitney in "A Dairy Tale Ending".
- This episode marks the first time that a pre-Generation V Pokémon besides Pikachu and Meowth has physically appeared in Unova.