Either Meowth or Clefairy-- marketable Normal-types with two-stage evolutions.
Or probably the starters.
So we all know Pikachu is the companies mascot, but what if they changed it? What would it be? What would you want it to be? I can say that some folks would pick Eevee, but try and go for something else. Can still say Eevee, but give another one also.