If you happen upon an unopened #Pokemon pack and notice a little black triangle on the bottom right, then it's your lucky day. Those packs are known as "Black Triangle Errors" and 1999 Pokemon Base Set Booster Pack Black Triangle Error Blastoise Art PSA 8 on Fanatics Collect 1999 Base Set Black Triangle Error Booster Pack Set PSA 10 The very first expansion to be released for the Pokmon TCG was Base Set (Expansion Pack in Japan), and in front Pokemon Black White Base Set Booster Box 36 Packs Pokemon USA ToyWiz