Pokeddexy Challenge Day 29: Scariest Pokemon - Gourgeist
Singing in eerie voices, they wander town streets on the night of the new moon. Anyone who hears their song is cursed.
It enwraps its prey in its hairlike arms. It sings joyfully as it observes the suffering of its prey.
I have a hard time finding any Pokemon scary, but Gourgeist is disturbing.