You can choose any animatornic you want and main key is: kill the nightguard.
It seems like easy, but not so, The nightguard has a mask in FNaF 2.
Following mechanics are canon, and you will be put in a restaurant like when you are a withered animatronic, you go to FNAF 2
If i am sure, i think Security Breach Works.
In security beach, you have to catch gregory, if you want to be glamrock freddy, then sure, help him. You can become any canon character.