Oh there are definitely more cute ghost types beyond these two. Yamask and the Misdreavous line immediately come to mind. Unfortunately, I don't have either of mine with me at the moment. Or most of my ghosts, I kind of have too many to carry with me all at once. But I do have two others with me.

[He pulls two balls off his belt, releasing his Sableye onto the table and his Dusknoir a few feet behind him. The Sableye sniffs the air, before catching sight of Perona and grinning up at her while the Dusknoir just kind of stares at her and floats.]

Gizmo is a Sableye, one of two ghosts with no elemental weaknesses due to their dual ghost/dark typing. [Gizmo puffs out his chest a little, glancing nonchalantly at his claws. Yeah, he's pretty awesome.] And Elliot is a Dusknoir. They're like the Pokemon equivalent of Grim Reapers, if the lore is to be believed.