So, while waiting for Part 4, I've relooked at the DeviantArt render LivingCorpse posted. Now, I know it's not up to date, but there are some interesting characters to find here. These are some that still weren't shown in any of the videos (to my knowledge) in this more accurate form (so no, I'm not considering the old Final Nights video for example):

FNAF 3:

• Shadow Freddy, FNAF 3 skin

FNAF World:

• Virtua-Freddy (Neon Chica was used as a placeholder in battles where the Mimic Ball was present, if I recall correctly)

FNAF: SL:

• Minireenas (probably a move only though, however I won't exclude the presence of Minireenas 2 as a character)

FNAF: SB:

• Glamrock Hippo

FNAF Movie:

• Balloon Boy Statue

FNAF: SOTM:

• Jackie (is it playable? I think so. But I'm not sure what the Mimic will do in the game)

The Joy of Creation:

I'm not exactly sure if I was the only one confused on what they were at first, but there are new TJOC characters, based on the Fanverse game and not the old ones:

• New Ignited Freddy

• New Ignited Bonnie

• New Ignited Chica

• New Ignited Foxy

• New Ignited Golden Freddy

• New Creation

POPGOES: Evergreen

• False(?) Toy Freddy

Five Nights at Candy's

• FNAC 2 The Rat (the first one was shown before)

Those Nights at Rachel's

• The Thing

Please comment if I've missed any playable characters in the render!