I'm not sure if this are the most accurate sizes of the Nightmare Animatronics, But I compared it to Derpy_Horse4's animatronic size to be exact but still not sure about the size,
Buy The Nightmare Before Christmas Mystery Minis at Funko.
Nightmare | Wiki | FNaF Amino [ Español ] Amino
Buy SNAPS! Nightmare Bonnie at Funko.
Nightmare Fredbear | Five Nights at Freddy's Wiki | Fandom
Personal Nightmare - Wikipedia
Nightmare Fredbear Concept by thewebsurfer97 -- Fur Affinity [dot] net