Butterfree and Me! (Japanese: サトシとバタフリー！また会う日まで！！ Ash and Butterfree! Until the Day We Meet Again!!) is the 33rd episode of Pokémon: BW Adventures in Unova and Beyond.
Having arrived on Migration Island, Ash and company encounter a bunch of Metapod who evolve into Butterfree and then fly off as a part of the island's tradition. They find a Caterpie who didn't evolve into Metapod yet. Reminding him about his old friend, Ash decides to help Caterpie train, so it can evolve and leave with its family on time. With several obstacles like Ursaring and Team Rocket, will Ash help Caterpie evolve?
The heroes continue sailing and encounter a flock of Swanna flying by. Porter is certain they are migrating, moving to a different place. Porter tells them that is Wayfarer Island, a resting stop for migrating Pokémon, or a home for newborn Pokémon before they leave their nest. The heroes come to the island's Pokémon Center, where Nurse Joy tells them they can find such Pokémon in the mountains. They go to the mountains and encounter a bunch of Metapod. They soon find them all evolving into Butterfree, pleasing the heroes they saw this wonderful event. The heroes are glad the Butterfree are flying off, but Ash notices a Caterpie, who can evolve into a Metapod.
The heroes are surprised it hasn't evolved with its friends. Ash remembers well Caterpie was his very first Pokémon he caught and had it evolve into Butterfree, though Butterfree flew off with a pink-colored one, as it fell in love with it. Ash wonders where Butterfree is now, but knows it has a good life with its mate. Ash realizes this Caterpie is sleeping and runs off to the Pokémon Center. He contacts Prof. Oak, but is startled by his Rotom at the screen. Prof. Oak scolds Rotom, who shocks him back. At any rate, Ash asks one of his Pokémon to be sent back. Ash comes back and seeing Caterpie still asleep, he wakes it up. Ash decides to help Caterpie evolve by having it battle.
Ash sends Leavanny, thinking he may be able to help Leavanny evolve. Caterpie is still asleep, so Leavanny uses Energy Ball to wake it up. However, Caterpie becomes scared and runs off. Ash, Pikachu and Leavanny seek Caterpie, who is sleeping on a tree. Caterpie wakes up and terrified of them, runs to the higher point of the tree. However, it hangs on a branch, which snaps. Caterpie falls down, but Ash rescues it, though bashes himself into the tree. Ash tells Caterpie he had a Caterpie before and cannot ignore it. Instead, he asks it for a training, which Caterpie agrees to. They come to a bush, where Caterpie eats some leaves, then takes a nap. Seeing Caterpie taking naps all the time, Ash and Pikachu do the same. After some Altaria and Swablu pass by, Caterpie wakes up. Ash has an idea, for a training - he, Pikachu and Caterpie climb trees.
Caterpie uses String Shot and swings from tree to tree. Iris does this with the vines, so Ash and Pikachu do it as well, but miss a vine and fall down. Caterpie uses String Shot and binds Ash and Pikachu, saving them from the fall. After a meal, the heroes come back to the Pokémon Center and sleep with Caterpie. The next day, Ash has another day with Caterpie before falling asleep at night. Team Rocket watched this and see Caterpie is taking too much time to evolve. They don't care much for Caterpie, as their real target is Pikachu. Next day, the heroes go with Caterpie to harvest berries. Ash and Iris see a claw mark, symbolising someone's territory. That someone is Ursaring, who chases them down. Seeing Caterpie eating its berries, Ursaring strikes, but Ash saves Caterpie and hides.
Ursaring passes by and is accidentally shot by Caterpie's String Shot, for Caterpie and Ash were hiding. Ash runs with Caterpie away from Ursaring. Caterpie starts releasing smell from its antenna, angering Ursaring even more, cornering them both to the end of a cliff. Caterpie tackles Ursaring and binds it with String Shot. Despite Ursaring freeing itself, Ursaring is hit by Pikachu's Thunderbolt and runs off. Ash thanks Pikachu and Caterpie, the latter evolving into a Metapod. However, Metapod retains the napping issue. At the Pokémon Center, Cilan and Iris heard next week a bunch of Butterfree will pass by, so if Metapod evolves by then, it could fly off with them. Ash is not certain, since Metapod naps more than it trains. Next day, the heroes run with Metapod and when they take a break, they notice the Butterfree flying to them. Iris suspects they used Tailwind, since they came here a week earlier.
Ash wakes Metapod up to conduct the special training, else it may not evolve and leave with Butterfree. At the end of the day, Metapod still hasn't evolved and takes a nap. Ash tries to get it to train, but Pikachu and Metapod get captured by Team Rocket. Team Rocket did not count to catch Metapod, but take it and place Pikachu in a cage. Ash runs and goes to their balloon, so James sends Amoonguss, who uses Body Slam on him. Ash does not give up, so Metapod, seeing its friend is in trouble, evolves into a Butterfree. Amoonguss hits Ash, who falls down, but is put to the ground by Butterfree's Confusion. Jessie sends Woobat, who uses Air Slash, but misses. Amoonguss uses Hidden Power, but also misses. Butterfree hits Pikachu's cage with Psybeam, rescuing Pikachu. Using Psybeam and Thunderbolt, Butterfree and Pikachu blast Team Rocket off.
The sun rises, waking the Butterfree up. Seeing its fellow Pokémon, Butterfree flies up. The heroes bid them farewell, but Ash is grim, since his new friend is flying off. Butterfree turns around and sees Ash, who runs to the cliff and bids it farewell. Butterfree flies off and Ash promises they will see each other again.
Who's that Pokémon?: Butterfree
The intro for the N arc was used.