When Mystique tried to save Toad, she too was genetically changed by Prosh’s machines. As a result her default state sported scales with slicked back hair. [X-Men Forever #6] Actually, this was done to make her look like in the successful movie adaption of the X-Men. It is unknown whether the scaly state is still her default form and Mystique only shapeshifts into her old template because she likes it more.