Most Disturbing ‘Pokémon’
You should probably know that Yamask isn't really a Pokemon in the traditional sense. It's actually a ghost of a human that died, holding a mask. The mask it carries is a representation of the one it used to have while living. Sometimes it stares at the mask and starts crying. Sometimes it possesses anybody who would wear it's demonic mask. The mask itself actually carries traces of the Yamask's human identity, and when it evolves into Cofagrigus it uses its sarcophagus body to lure in humans and Pokemon. Then it turns them into zombified mummies.