All the Nightmare Animatronics are fidgets of CC's imagination, so they are based upon F&F Animatronics. I am going to be listing the Animatronics the Nightmares are based upon:
Nightmare Freddy: Freddy Fazbear (springlocked) (Later becomes Rockstar Freddy)
Freddles: Freddy Plushies
Nightmare Bonnie: Bonnie The Bunny (springlocked) (later becomes Rockstar Bonnie)
Nightmare Chica: Chica The Chicken (springlocked) (later becomes Rockstar Chica)
Nightmare Cupcake: Mr. Cupcake
Nightmare Foxy: Foxy The Pirate Fox (springlocked) (later becomes Rockstar Foxy)
Nightmare Fredbear: Fredbear (springlocked)
PlushTrap: Springbonnie Plush
Nightmare BB: BB The Balloon Boy (springlocked)
Nightmarrionne: The Puppet (later was stuffed into Lefty)
Nightmare Mangle: That broken toy thing in Elizabeth's room.
Nightmare: Some old F&F Animatronic, most likely an early version/draft of Lefty