Slater

Slater is a secondary antagonist in FNASH 1 and 3.

Before FNASH 1
Before FNASH 1, Slater was a Nintendo, Pokemon, and Undertale fan. Him being a fan of Pokemon is assumed to be the reason for why his body is a Pikachu when he's Reformed.

In FNASH 1
In FNASH 1, Slater takes on the appearance of a Pikachu from Pokemon, but with Slater's face. He acts differently from the other Monsters. Instead of trying to get through the Doors, he has a Nintendo Switch in the Living Room. You have to check back on the Switch every once in a while to recharge it, otherwise Slater will kill you, similar to The Puppet from FNAF 2.

In FNASH 3
In FNASH 3, Slater is a Ruined Monster. Several Pikachu heads sprout from his back, along with the typical fragmentation. In this game, Slater roams around like the rest of the Monsters, only he enters your room through the back door.