Here's what I personally think about what would be the bosses for each level in Dark Deception Chapter 4.
Let's begin...

The boss for The Asylum could be the original "Big Nurse" model because she's confirmed to not being cut from the game.

The boss for The Asylum level could be a mad surgeon.

The boss for The Asylum level could be a crazy doctor.

The boss for The Restaurant could be a wolf animatronic.

The boss for The Restaurant could be a bear animatronic.

The boss for The Restaurant could be a moose animatronic.

The boss for The Restaurant could be a lion animatronic.

The boss for The Restaurant could be a jackal animatronic.

The boss for The Restaurant could be an owl animatronic.

The boss for The Restaurant could be a beaver animatronic.

The boss for The Restaurant could be a goat animatronic.

The boss for The Restaurant could be a dog animatronic.

The boss for The Restaurant could be a bull animatronic.

The boss for The Restaurant could be a raccoon animatronic.

The boss for The Restaurant could be a cat animatronic.

The boss for The Restaurant could be a sea otter animatronic

The boss for The Restaurant could be a tree animatronic.

The boss for The Restaurant could be a cyborg.

The boss for The Restaurant could be an angry farmer animatronic.

The boss for The Factory could be Mama Bear herself.

The boss for The Factory could be Papa Bear(Terror Teddy) himself. Also, this is an art by Devon the Adventurer.

The boss for The Factory could be a factory Power Loader mech controlled by a Trigger Teddy from the inside.

The boss for The Factory could be a pile of plushies similar to Gurdy from The Binding of Isaac