Pokémon "Rocket-dan VS Plasma-dan!" (partially found unaired two-part episode of anime; 2011)
Premiering in Japan on September 23, 2010, was the 4th 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 and tsunami, 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!.
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. There's not a whole lot more information available on the episodes, though 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".