Some episodes in the Pokemon series were banned because of numerous reasons.
 Banned Episode(s) in AmericaBeauty and the Beach
When the episodes for the Anime were first being dubbed for airing in North America, this episode was originally banned due to James wearing an inflatable body suit, which gave him abnormally large breasts to try and win a beauty contest. The episode was dubbed, and aired twice in 2000, but disappeared once again.
This episode rarely seen.
Tentacool & Tentacruel
This episode was taken out of rotation following the September 11th attacks on the World Trade Center, the Pentagon, and Flight 93. As a result of the attack, Kids' WB! (the network that was airing Pokémon episodes at the time) refused to air this episode due to the destruction of several buildings in general, and Tentacruel smashing a skyscraper in particular, along with the usage of projectile weapons, including machine guns. Nastina also used large-scale assault weapons during the fight scenes in the episode, including a tank. However, Tentacruel striking a building was not removed from the opening theme, and the episode is still readily available on the home video and DVD markets. This episode also aired on Cartoon Network at least once.
This episode is no longer banned.
The Tower of Terror
This episode was banned temporarily after the events of September 11th. An official reason for this temporary ban has never been confirmed, but it is widely believed that the episode's title could have had something to do with it.
This episode is no longer banned.
The Legend of Dratini
This episode was banned due to the prevalent usage of projectile weapons throughout the episode, specifically handguns. The Safari Zone warden points a gun at Ash's head, and goes as far to shoot said handguns at Team Rocket. The banning of this episode left a major plot hole because in this episode, Ash captured all 30 of his Tauros. Additionally, this is the Safari Zone episode, which makes the Safari Zone unseen in the English anime, though it is mentioned in the two prior episodes.
This episode has never been aired in America.
This is the only episode of Pokémon to be banned in America after its first airing. After the episode aired, a woman named Carole B. Weatherford wrote an article stating that Jynx, which was featured prominently throughout the episode, is a stereotype of African-Americans.
This episode is banned in both America and South Korea.
The Ice Cave!
This episode was also banned due to the large focus on Jynx. Unlike the previous episode, this one has never aired in America. This episode was not seen outside of Japan except for Brazil due to Jynx not having its re-designed purple skin.
The episode was also banned because of the disease influenza going around (the symptoms were SARS-like). In this episode Team Rocket doused Ash and his friends with cold water inside an icy cave, causing Brock to come down with symptoms similar to influenza. Though according to Carole Boston Weatherford, the SARS part is a myth, and the episode was skipped due to the controversial version of Jynx.
This episode is banned.
 Banned Episode(s) in JapanComputer Soldier Porygon
Known as the "seizure episode," this episode has been banned worldwide after airing only once in Japan. One particular scene of this episode had a series of flashing lights, which caused approximately 700 Japanese children
to be sent to the hospital with symptoms of epilepsy. The show went on hiatus for months and was almost cancelled, and delayed the episodes Holiday Hi-Jynx and Snow Way Out. The episode also forced the producers to go back through the previous episodes and dim the lighting on them so as not to cause an accident of this magnitude again.
This episode is banned worldwide
Shaking Island Battle! Barboach VS Whiscash!! (unaired)
This is the only episode of Pokémon to have never been aired. Not long before this episode was scheduled to air, a devastating earthquake struck Japan. Believing it would have been insensitive to air an episode about earthquakes mere weeks after the disaster, it was postponed. However, it never got around to airing and was soon forgotten.
This episode has never been aired worldwide.
 Banned Episode(s) in Other CountriesThe Bicker the Better
This episode has been banned in several countries, including Italy, France and Aruba. It's been alleged that the "battle of the sexes" format of the episode has caused those countries to ban the episode.
This episode is banned in Italy, France, and Aruba.
South Korea also banned the episode Challenge of the Samurai due to the episode's featuring of a samurai, and the episodes Pokémon Scent-sation, The Ninja Poké-Showdown, Riddle Me This, Bad to the Bone and The Fourth Round Rumble on the grounds of cultural and racial discrimination.