A muppet version of good omens were everyone is a muppet except for all the angels and demons.
All angels and demons are play by humans but whenever they are on earth they carry around a little muppet version of themselves Avenue Q style, because those are their corporations.
So Aziraphale and Crowley are still Michael Sheen and David Tennant but they puppet around muppet versions of themselves.
Whenever they are speaking to each other or to other demons and angels they are just talking with their actual faces and normal voices but when talking to a human/muppet they put on exaggerated little voices and the muppet/humans will exclusively address their muppet corporation, not acknowledging the full grown human men puppeting them.
- There are no muppets in heaven or hell
- When Aziraphale possesses Madame Tracy he just starts puppeting the Madame Tracy muppet.
- Adam is just a human child, he doesn’t even have a muppet version of himself. He’s just a human child in this world of muppets and no one ever acknowledges it, not even Aziraphale and Crowley or Adam himself.
- Dog starts out as a real dog but then shapeshifts into a muppet dog.