Pokémon "The Legend of Dratini" (non-existent unaired English dub of anime episode; 1997)
The Legend of Dratini was a controversial episode of the Pokémon anime that aired in Japan in 1997, but was never broadcast outside of Asia. The episode was banned by the American dub company 4Kids following a controversial scene, which included Ash being held at gunpoint. This, unsurprisingly, did not get past the 4Kids censors, and thus did not air. As all countries outside of Asia air dubs based on the English version it was never shown outside of Asia.
4Kids used footage of this episode in the Pokérap which means that they got the episode from Japan. There is no indication that the episode has been dubbed.
The Japanese version is available on YouTube, however. The closest to an English dub on YouTube is the Japanese version with English subtitles.