To uncover one of the greatest secrets of evolution, Ash goes to the Seafoam Islands where he meets up with Misty and Brock (who left him in training for the League). They meet up with Professor Westwood V, who is on the brink of discovering why Shellder goes to bite Slowpoke's tail to evolve. On the other hand, Team Rocket are assigned to capture a Slowpoke and evolve it for the boss. Will their plans work this time?