Would you ever do a preevolution for Type Null? Surely it's not born with the mask on. And it's got to have an actual name instead of just Type Null.
I don't think a pre-evo would really fit well for Type: Null since it's an artificial Pokemon that was created as Type: Full (Silvally) and then fitted later with the limiter helmet and dubbed Type: Null.
But if someone commissioned a baby Type: Null, I think it would look like a small, cute, plainer Silvally either without a helmet at all, or with a simpler type of helmet/restraint or testing equipment attached.













