The animatronics will have minor damage details like dirt, scratches, minor spasms, etc.

They will not have any eyes and will always limp towards you. The more progress you make the worser their states get.

Night 1: The animatronics have minor body scratches and some dirt, some short spasms come, being too close to the animatronics results in you hearing cries for help and screams and even your own heartbeat. The longer your closer to them, the worser your condition gets.

Night 2: the animatronics seemingly have burn patches around the body, you can notice small splatters of blood in the joints. And the animatronics have more serious spasms.

Night 3: The animatronics always spasm, and they are bleeding even more, they also seem to limp but still move faster. They have lots of visible dirt and damage. The blood is now dripping onto the tiles. This is good for finding where the animatronics went to when you have no access to cameras.

Night 4: The animatronics seem to be faster than you. They always leak blood and stall from time to time, they seemingly develop tentacles which I presume to be from the marrionete. For instance Fredbear will stall and then tentacles emerge from the majority of his joints. He will have lots of sparking from spasming and will look like a zombie at this point.

Night 5: the animatronics now have a speed faster than the player. And they have glowing eyes despite not having any eyes. They will also look very broken and have stuff like broken jaws, cracks and wiring meshes visible. Even more stalls and more tentacles emerging. They are more hostile and have somehow gotten claws from both hands.

Night 6: they are all shadow animatronics so their entire body is just a shadow. The curse absorbed their bodies whole.

Night 7: depends on the state you give to animatronics.

NOTE: This is an idea and to show signs of lore and progression of the toughness of them demons.