I can see story possibilities in all of these.

None of these make sense in the SLIGHTEST. You could MAYBE push Scooby-Doo or Ghostbusters, but it still makes absolutely zero sense

We already have Shaggy's actor playing as William. What more do you want?

@Chibi Funtime

This just reminded me of that Fan Film I saw somebody make with the Ghostbusters crossing over with Fnaf but I unfortunately don't remember what it was called because it has been ages since I last saw it lol.