Because ghosts don't have shadows.
Dark and ghost. Yes, ghost is weak to itself.
Dark, and ghost.
Ghost types are fundamentally weak against ghost or dark attacks.
Ghost-type Pokemon are weak against Ghost and Dark-type moves.
Because Ghost Pokemon can't see in the dark.
Ghost-type Pokemon are weak against Ghost and Dark-type moves.
Ghost and Dark. Dark is immune to Psychic attacks.
they are weak to fighting and bug. They are immune to psychic. They resist dark and ghost. They have no weaknesses if they are dark and ghost.
Ghost and Dark types., (Yes, Ghost is weak to itself).
Bug, Ghost, and Dark.
Ghost-type Pokemon are weak against Ghost and Dark types.
Ghost types are weak against other Ghost type moves along with Dark type moves.