Pokémon "Rocket-dan VS Plasma-dan!" (partially found unaired two-part episode of anime; 2011)
Premiering in Japan on September 23, 2010, was the 5th generation of the Pokémon anime, known as Best Wishes! During its initial run, there was scheduled to air a 2-part episode in March 2011, ("Rocket-dan VS Plasma-dan!", "Team Rocket vs. Team Plasma!" translated, Parts 1 and 2 respectively), revolving around Team Rocket fighting Team Plasma over possession of a meteorite. However, following the devastating 2011 Tōhoku earthquake, tsunami and nuclear plant meltdown, both episodes were postponed for featuring scenes reminiscent of the disaster. As such, Team Plasma didn't end up appearing until near the end of Best Wishes!, and appearing as they did in the Black 2 & White 2 video games as opposed to their Black & White incarnations.
According to Pokémon's English dub voice director Tom Wayland, the episodes were sent to The Pokémon Company International, but never actually got to the re-dubbing process before their cancellation in Japan. Many screenshots from upcoming previews and magazines have managed to find their way online.
These episodes are 2 of 4 Pokémon episodes that have never aired, the other 2 being "Battle of the Quaking Island! Barboach VS Whiscash!!" and "It's New Year's Eve! Pocket Monsters Encore". However, it is still possible that these episodes might air someday in the future, as both the Pokemon Company of Japan and TV Tokyo maintain that when they will broadcast them when an airdate is decided upon if contacted via e-mail, and in both re-runs and on DVD the preview teaser for Part 1 still plays at the end of the episode that preceded it. But sadly, it is far too late for these episodes to ever be dubbed internationally, as the preceding episode had its ending altered in the dub so as not to have its events lead in to the events of the postponed episodes. The dub has since concluded the 5th generation of the anime and moved on.
Allegedly after much digging around on the Japanese internet, a Tumblr user acquired a synopsis of the episodes from anonymous sources and posted it online. Evidently, the chief reason behind the episodes being pulled from the air was the effects of the artifact known as the Meteonite, which emitted radiation-like energy which threatened to destroy a big city. This was naturally deemed far too inappropriate to show directly following the Fukushima nuclear plant meltdown.