Although predatory pokemon and a vast number of large herbivores are capable of turning the living into ghosts – at least if their spirits choose to remain in this world – only Pumpkaboo and their evolved form of Gourgeist can do so on a temporary basis. These pokemon possess a mysterious attack which is capable of briefly snatching the life force from a living pokemon, while leaving the soul connected, creating a unique form of undead for every species of pokemon it affects.
It has long been rumored, although never reliably substantiated, that Pumpkaboo are just as capable of using this technique against Man, for like some warped facsimile of a missionary they wish for everyone to experience a ghost's existence, even if only for a mere hour at best. A few mystics have become converts to the Pumpkaboo way, and claim to use temporary ghost status to facilitate out-of-body experiences – for most humans, however, the thought of even a temporary death is the source of profound terror, and the Pumpkaboo are too numerous and dangerous to ignore.
For this reason, once every year, the people of Kalos deceive the Pumpkaboo by dressing as various representations of undead humans, in a grand festival aimed at deceiving the Pumpkaboo into thinking their services are no longer required. In this era, it has often been associated with the candy-stealing holiday of the Simisear, for they are both held around the same time of year and involve costuming; many traditionalists in Kalos fear that the festival has drifted too far from its original purpose, and will soon fail to convince the Pumpkaboo that humanity has sufficient experience with the world of the dead.