The Evolution Solution (Japanese: ヤドンがヤドランになるときWhen Yadon Becomes Yadoran) is the 66th episode of the Pokémon anime. It was first broadcast in Japan on October 15, 1998 and in the United States on October 2, 1999.
Spoiler warning: this article may contain major plot or ending details.
Ash and Pikachu head to the Seafoam Islands and startle Brock and Misty into falling off their surfboards. They go to Westwood’s lab to discover he is the fifth of many Westwoods, and he insists to be called that. He happens to be researching the Slowpoke and Shellder, too. Somehow, a Shellder bites Slowpoke’s tail and it becomes a Slowbro.
Meanwhile, the Team Rocket boss is taking a vacation and making Jessie and James dig for clams. They find a Shellder and James decides to try to capture it. James copies Ash to call out Weezing. James defeats the Shellder, but Jessie steps up to capture it. They go to the boss, but he is annoyed with them as usual. He tells them to steal all the Pokémon from the lab. They find that all Professor Westwood has is a Slowpoke. They send out the Shellder to make it evolve into Slowbro. They have a hard time with it, and it clamps on Psyduck’s head, giving it a major headache.
Psyduck uses Disable to stop everyone, but then the Shellder clamps onto Slowpoke’s tail, evolving it. Slowbro uses Mega Punch and so Team Rocket blasts off again. Westwood figures out why Slowpoke evolves, which is because both Pokémon benefit: Shellder balances Slowpoke so it can use Mega Punch, and Shellder gains transportation on Slowpoke’s tail.
In the beginning of the scene where Giovanni is yelling at Jessie and James, he is barefoot. He is shown later in that same scene with blue sandals on.
Dub edits
In other languages
Finnish: Evoluutiomysteeri
French: Le mystère de l'évolution
German: Rätselhafte Entwicklung
Italian: Una grande scoperta
Latin American Spanish: ¡La solución de la evolución!