>>29032493Likely, the idea was that Ghost was supposed to be the offensive counter to Psychic (bar any bugs that caused Psychic to be immune instead) so they made it what Psychic is typically lacking - Physical. Dark being physical as well as immune to Psychic was overkill, especially with Steel being introduced as well, so they made it Special.
Also, the original gen each type came out had a typeless move; Night Shade does set damage and Beat Up wasnt actually a Dark move until gen 5.
