>>48525696It still eats, sleeps, and reproduces like any other Pokemon. It WAS dead, but then it came back to life in a new form. That's how becoming a Ghost-type Pokemon works. You don't "die", your spirit just manifests into a new form.
There are actual dead ghosts in this series and they're completely different from Ghost-type Pokemon because they can't battle, eat, or interact with the living world in any way, like the Marowak ghost.