The main flaw with this theory was due to Shuppet having eyes. Well, not anymore! Shuppet's eyes aren't ACTUAL eyes, but rather Rotom's layers! The final light blue shade in the eye is the interior of the cloak being illuminated by Rotom. Shuppet's mouth is also the crease created by Rotom's bottom half.
Both are floating Ghost types. Shuppet can't use electric attacks because the cloak blocks them. Shuppet can't invade a fridge because Rotom is trying to infiltrate the cloak.
Take that, sheeple!
Pic related