User blog comment:YngweeTDP/What suit do the purple guy wear?/@comment-28920015-20170618185458

Uh huh.

Well all the evdence we have points towards the "yellow costume" being Springbonnie. We know it can't be Golden Freddy unless Fredbear and G. Freedy are one in the same, but even then in the FNaF3 minigames we see Purple Guy ran into a springbonnie suit, and unless Michel and William used diffrent suits, how are we to know that yeah, Fredbear ​AND  Springbonnie were used?

We can cross off any other suit because as of now, we have no knowledge of any other Spring-locks, the only ones that can be worn as costumes, mind you.

So unless Scott Cawthon comes out and says, "Yeah there's more springlocks." Our best bet right now is that William Afton wore a Sprinngbonnie spring-lock.