Episode Name: US: Beauty And The Beach, JP: Holiday At Acopaulo
This episode was banned because it shows James of Team Rocket with clevage put there so he can enter and win a beauty contest. It was deemed unfit for children. The images of James took up a lot of the episode so when a cut version was aired in America it was messed up and extremely short.
Episode Name: The Legend Of Dratini
This episode was banned because of the overuse of a gun. Other episodes use guns but this episode showed the gun being used or shot at another person. Because there were many shootings in the US where guns were used by children they decicded not to air it.
Episode Name: Electric Soldier Porygon
This episode was one of the most wide known and is banned everywhere including Japan! The episode featured Pikachu firing a Thunderbolt at a missile that was launched at Ash & co. by Team Rocket, therefore causing flashing of red and blue. This flashing put over 800 Japanese children into hospitals with epileptic seizures and nearly caused Pokemon to be banned forever.
Episode Name: The Ice Cave
League: Johto - Master Quest
No one knows why this episode was banned but many people think that it may have been because Brock nearly kissed a Jynx, thinking it was Nurse Joy when he was ill. Others believe that it was banned in the US because Team Rocket gave Brock Hypothermia intentionally and at that time there was a SARS epidemic. It was therefore unfit for airing at that time.
Episode Name: Shaking Island Battle! Barboach VS Whiscash!
At the time this episode was supposed to air in Japan there were earthquakes. The episode features Whiscash making earthquakes, so they felt they couldn't show it. It hasn't been aired anywhere since, not even in Japan.