This is grade AA, top tier shitpost which means over analyzing is my specialty.

First I read it as "Ghost of Chris Pratt" and the answer is yes, it would be a normal ghost.

Then I read it correctly as Ghost of Christmas Past, and my answer is - maybe, but the ghost is able to bring the victim into events of their past lives, I think he could take Pac-Man back to a time where he ate a ghost that he didn't realize what he had done, make him regret eating ghosts and prevent the ghost of Christmas past from being eaten at all.

1. Slimer - yes, regular ghost, just messy and he'll need a napkin.
2. Do you mean Samara? Or is this a different The Ring. If Samara - yes, seems to follow the same rules as the ghosts in Pac-Man.
3. Yes, he could, but that would imply Pac-man sleeps and dreams. If he doesn't do those things how will he interact with Freddy pointy hands?
4. No. The clown from "It" is an established demon, not a deceased person bound to this world.
5. No. The ring wraiths are a weird kind of undead in that they are multiplaner and still both men yet their bodies no longer exist in our plane, yet have some sort of magic clothing that gives them form in our world. Essentially they didn't die, so they aren't ghosts.

Over analyzing shitposts is my specialty