The Mundane but Correct Explanation for Nightmare BB's Canonicity

Every now and then Nightare BB's canonicity will come up in theory discussion. So the story goes: Scott has confirmed that, while the FNaF4 Halloween Update characters are generally noncanon, Nightmare BB is the single exception. How strange! How queer! What is narratively unique about BB, as opposed to Mangle and Nightmarionne and the Jack-o's, that he specifically is canon, and not the others?

This seems like a fascinating, perplexing question, until you realize it has a very mundane answer.



The FNaF4 Halloween Update has 2 parts.

First, there's the challenges and cheats, and the Fun with Balloon Boy minigame, which you access from the Extras menu, used to skip hours on challenge modes. These are permanent additions to the game, accessible any time of year, and can be considered canon.

Second, there are the temporary changes which appear only on October 31. The Nightmare animatronics are swapped out for their Halloween counterparts: The Jack-o's, Mangle, Nightmarionne, and BB. These are temporary festive changes which replace the standard gameplay on Halloween. They overwrite the established canon characters; thus, they cannot be considered canon.

Nightmare BB is the only one who can be considered canon because he's the only one with a separate gameplay mode which was permanently added to the game, rather than just overwriting existing characters on Halloween.