so, i've taken a lil' peek at the game's enemy sprites (and the enemy "code") and i found this 'Happy' thingy. yet-to-be-used content, red herring, or a secret boss i missed?
edit:whoops i done discovered it
you fight it in the mall second floor the part of the back rooms area it had around 80,000 health for me but stunlocking it always worked for me
its doom attack did like 2,000 dmg