Who is it that runs the spirit realm
Ah, so THIS is why my stomach buzzed at me! I keep forgetting I have this lovely little device, hahaha!
Well... Nobody, technically. It's a bit of a difficult and a winded question to answer- but I am glad I'm able to answer it, that's certain!
It's... hmm. The Spirit Realm is, as we all know, the resting, restoration, and dissolving place for all spirits and Ghosts. A place such like that is filled to the absolute brim with magical energy! Specifically, the energies associated with spirits and life, the same sort of thing that Vitalivore feed off of.
With such an absolute abundance of energy and such a lack of order, the spirit realm sort of... formed itself into physical being.
Multiple physical beings, actually! The main 'hand' of the spirit realm is another Dusknoir; a very large one, too, with lots of arms! There's a few others- I think one's shaped as a Mismagius, at the very least. The one specifically in charge of my business is a Dusknoir as well, but I think they were a normal Pokemon that was promoted.
By nature of their, well, existence, they're unable to cross the threshold into the mortal plain themselves- but are able to inhabit other ghosts to peer into it if needs be. Luckily, there's almost never any reason that needs be.