I should have been more clear in my comment. If there are two distinct colors other than white, I would consider the marble a Prizename, even if it's on a white base. And don't worry about any comments to me - my feathers don't ruffle very easily. 🙂
My son, Jake, was a huge Pokemon fan too, and I always enjoyed playing with him. When he passed, he left behind a gigantic collection of cards. It took me weeks to sort and catalogue them. I sold all of the less valuable ones but kept a few hundred others. At one point, he had two complete first edition base sets, jungle sets, and gym sets. But he traded or sold most of them off to support his car and girl ambitions as he got older.