You know what? I think that he stuffed them in suits for a reason, not just to hide the bodies. In the book series, the animatronics run on the power of agony. This means that even animatronics that don't have a spirit in them will move and try to cause more agony, leading to more power, and so on. This might be the same in the games, but the children are partly controlling them. They require agony in them, so Purple Boi gave them all a powerful source - the kids in each animatronic.
