Gold W Pokemon Cards Pokemon Cards: Pikachu Card With A W On It And Others With Silver Triangles?

Pokemon cards: Pikachu card with a W on it and others with silver triangles? - gold w pokemon cards

I store a large box of Pokemon cards in a thrift, and one of them a Pikachu Forest Gold is stamped with a W on it. I know it is a kind of map production, I was just curious to see how in the time they were acquired discharged.
Some other cards silver triangles PK repeated on the front or rear, the lower left corner. A Ninetales its front and two Cloyster CV and Sandslash. I also wonder how they obtained when they were published.