Toy Bonnie in FMR is found by interacting with his mask at the Birthday Hall, then locating three hidden Toy Bonnie spots around the map and finally selecting him from the character menu after resetting. The sources I found point to the Party Room/Employees Only area, the Kitchen, and then the menu scroll as the key steps.

Where to look

  • Birthday Hall first, where the Toy Bonnie mask starts the challenge.
  • Employees Only room near the Party Room area for one hidden Toy Bonnie.
  • Kitchen for another hidden Toy Bonnie.
  • Character select menu after you reset, where Toy Bonnie appears once the other steps are done.

Simple route

  1. Go to the Birthday Hall and inspect the Toy Bonnie mask.
  1. Find the first Toy Bonnie in the Employees Only room by the Party Room.
  1. Find the second one in the Kitchen.
  1. Reset and check the character menu for Toy Bonnie.

Note

Some guides mention this as Secret Character XV, which is Toy Bonnie in FMR.