Banned episodes

Many episodes of Pokemon have been banned for whatever reason

Denno Shenshi Porygon (Computer Soldier Porygon)
This episode is infamous for causing many seizures when first aired. In the episode, Pikachu, in order to stop some missles, uses a Thunderbolt attack. This leads to a very large and quick sequence where lights flash very quickly and vividly on screen. Some of these lights were strobe lights being flashed at very high speeds. The episode has never been shown again and has set guidelines for flashing lights in anime. To remove the episode from the public mind, the character Porygon has never appeared again over the course of the series.

Yureru Shima no Tatakai! Dojoach Vs Namazun!!
This episode revolves around a bunch of Whiscash causing an earthquake. It was removed and never aired anywhere, including Japan, due to similarities to the Chuetsu earthquakes of October 23, 2004.

Beauty and the Beach
This episode revolves around all the female characters entering a swimsuit competition, James, in order to enter, buys a pair of inflatable breasts. The episode is famous for one scene where James is waving his fake breasts in others faces for comedic effect. The image has become a quite popular GIF on the internet.