At the Cerise Laboratory, Mimey leads the rest of the group through some morning kung fu exercises. Mimey points out that Metapod's pose is perfect, leaving everyone confused as it doesn't have any limbs. Unexpectedly, Scorbunny kicks Metapod into a rock, sending everyone into a panic. As Professor Cerise mistakenly tries nursing the rock, Metapod assures Goh that it's fine.
Goh gets a big surprise when Ash tosses him his bag, and says they're heading for the Hoenn region. They arrive at the Hoenn Battle Frontier, in time to compete in the Battle Frontier Flute Cup. Ash plans on entering with Pikachu and Mimey while Goh hopes Scorbunny and his Scyther will do well. Goh isn't feeling as enthusiastic as Ash, but that subsides when a Taillow swoops by. He chases after it, and with one Poké Ball he makes the catch. As his Pokédex updates, Goh learns that Taillow eat Wurmple, so he calls Taillow out to catch himself a Wurmple. Goh and Scorbunny walk directly into a Mightyena, and it becomes angry after Scorbunny pulls out a tuft of its fur.
Meanwhile, Ash meets a Trainer named Hodge, who is riding on his Hariyama's shoulder. He orders Ash to move away from the bins. Hodge has Hariyama lean forward, so he can throw away a drink bottle, only to fall face-first into the bin. Ash pushes the bottle into the recycle bin and is left stunned by Hodge's quick recovery. Afterward, Hodge introduces himself, revealing he is from Lavaridge Town. Hodge reveals that he is also entering the Flute Cup, only revealing that he will be using Hariyama. The Mightyena from earlier, followed by Goh and Scorbunny, leap into view. As Goh prepares to catch Mightyena, Hodge intervenes, admitting Mightyena is already his Pokémon. Goh then shows off his new Taillow, and Hodge comments on Goh's sincerity. Scorbunny prepares to kick Hodge for the snide remark, but Mightyena's snarl stops it, and it instead kicks Ash. Pikachu tries to defend his Trainer, but ends up electrocuting Ash.
Soon, Hodge gets an update of his phone, and he learns that he is up against Goh in the first round. The Battle Frontier Flute Cup soon gets underway, with Hodge’s Mightyena battling Goh's Scyther. Goh takes a moment to consult his dex, and learns that his Bug-type Scyther has the advantage over its Dark-type opponent. Goh decides to play it safe by having Scyther boost its attack power with a Swords Dance. Though Mightyena just rushes in, dealing a single knockout blow with Fire Fang. Goh apologizes to Scyther before recalling it back. Next, Goh sends out Scorbunny. It prepares to land a Double Kick, but is struck back with a Snarl attack. Mightyena follows up with Crunch, helping Hodge advance to the next round. Goh is left speechless by the defeat, and kneels down to comfort his fainted Pokémon. Despite his Pokémon making an instant recovery after a visit to the Pokémon Center, Goh is struggling to cope with his swift loss. He remarks that catching is better than battling. He rushes out to catch himself a Wurmple, ignoring Ash's request that he watch the matches.
Later, Ash and Hodge have breezed through the rounds and now face each other in the finals. Goh returns to the stadium in time to watch the match unfold. Ash leads with Mimey, while Hodge chooses to go with Hariyama first. Hodge orders a Force Palm, which Mimey easily avoids. Hariyama starts firing out a barrage of Force Palms, but Mimey continues to dodge them all with its kung fu techniques. Ash calls for a Focus Punch, and Mimey delivers a direct hit. Hariyama tries an Arm Thrust, but Mimey’s Reflect stops it from doing any damage. Mimey continues to trap Hariyama with Reflect walls before using Psychic to deal the finishing blow. Like Goh, the commentator is astounded, and even remarks that he has a newfound respect for Mr. Mime.
Hodge calls out his Mightyena. Though Mimey has seemingly lost its will to battle, Ash sends Pikachu onto the field instead. Hodge starts with a Snarl, though Pikachu swiftly evades with Quick Attack and lashing Mightyena with an Iron Tail. As he descends back to the field, Pikachu uses Thunderbolt, which proves powerful enough to blow a hole in the stadium’s ceiling. Hodge calls for a Sucker Punch, so Mightyena speeds around Pikachu, almost invisible as it bides its time to attack. As Sucker Punch hits, Pikachu is thrown into the air. Ash orders an Electroweb aimed at the ceiling, allowing to rebound with added velocity. Pikachu uses Iron Tail to smash directly into his opponent, knocking Mightyena out and winning Ash the Flute Cup. Idol Hibana awards Ash a set of five flutes in honor of the victory. Hariyama stomps towards Ash at the winner’s podium, before Hodge offers a handshake. However, Hodge leans too far forward and hits the ground.
Afterwards, Goh congratulates on the win and admits Mimey put up a great performance. Goh adds that battles really are fun, marking a real change of heart for the young Trainer. By nightfall, the boys return to the Cerise Laboratory where Goh proudly displays his three Wurmple. Chloe cannot understand why he caught three of the same Pokémon. Goh replies that it's part of a back-up plan that takes into account that Wurmple's evolutionary pattern into either Cascoon or Silcoon is unpredictable. Suddenly, Ash says it look like the Wurmple are evolving, but quickly reveals that he was joking. Scorbunny kicks Ash for the bad joke, while Mimey plays Ash's Red Flute.