This was shown on All Nippon Airways (ANA) domestic flights from August 1-31, 2004, and is titled "Pikachu's Summer Festival", the story is as follows:

The Pokemon festival takes place today on the beach and all the Pokemon like Pikachu, Plusle and Minun help to prepare the festival. The idol that is going to sing that night, is Azumarill. Azumarill is on the way to the festival, together with Meowth and Wobbuffet, but they get stranded on the way, things get even worse when a Skarmory flies towards Azumarill and takes him away! Pikachu, Plusle and Minun are going to rescue Azumarill, since without Azumarill the festival wouldn't have a star...

Source: Pokejello.com

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Parent story: Pocket Monsters Advanced Generation