Ep 28. Gettin' The Bug's Out

In Pokemon the Series season 3 episode 28, titled "Gettin' The Bug's Out," Ash, Misty, and Brock have made their way to Azalea Town, where the Azalea Gym is located. When they arrive, they find out that the Gym Leader, Bugsy, is out on a bug catching trip. The group decides to explore the town in the meantime.

While walking around, Ash and co. come across a research lab that studies Bug-type Pokemon. They meet a researcher named Cassandra, who is having trouble keeping her Bug-type Pokemon healthy. She is worried that something is wrong with the food that she has been giving them. Ash offers to help and the group sets out to find out what is causing the problem.

They discover that a rival researcher, named Professor Sebastian, has been sabotaging Cassandra's research. He has been sneaking poison into her Bug-type Pokemon's food in an attempt to make them weaker and slower than his own. Sebastian believes that only the strongest Bug-type Pokemon should be studied, and he will do whatever it takes to make sure his Pokemon are the best.

Ash, Misty, and Brock team up with Cassandra to stop Sebastian and find an antidote for the poisoned Pokemon. They devise a plan to sneak into Sebastian's lab and steal the antidote. With the help of Cassandra's Pokemon, they successfully break into the lab and retrieve the antidote.

Back at the research lab, the group administers the antidote to Cassandra's Pokemon, saving them from being permanently weakened. They confront Sebastian and expose his plan. He is arrested for his actions and Cassandra thanks Ash and co. for their help.

With the Bug-type Pokemon healthy again, Ash decides to challenge Bugsy to a Gym battle. However, when they arrive at the Gym, they find out that Bugsy has yet to return from his bug catching trip. The episode ends with the group waiting patiently for Bugsy's return so Ash can challenge him for his next Gym badge.