The Great Pokémon Holocaust occurred when the creature known as Mewsevenmillionthreehundredthousandtwo went batshit crazy and started tearing Coruscant a new biologically-superfluous orifice. Thousands were killed by the marauding beast, while thousands more were killed by the only thing that could put an end to the creature, an orbital bombardment from a Star Destroyer. Emperor Palpatine used a mind trick to make everyone on the planet forget that it had happened, but after the liberation by the New Republic, Luke Skywalker undid the trick.