Raichu, Golduck, Psyduck, Energy Search are the most abundant of the 1999-2000 copyright Fossil Cards due to appearing in the Thunderstorm Gift Box. However technically one could say there are 2 variants of the 1999-2000 Copyright Raichu,Golduck, Psyduck, Energy Search, the one from the Thunderstorm Gift Box and ones from actual Red-Logo Australian Fossil Packs due to a difference in card stock. The 1999-2000 Fossil cards from the Red-Logo Packs have a different card stock and feel different, its pretty obvious if you have a physical copy with you.
I just acquired a PSA 10 Raichu copy from a red logo pack. Are there any visual differences between the Red-Logo pack and the Thunderstorm Gift Box? The Red Logo pack Raichu was the last card I needed to have all of its English variants in PSA 10 but if the Thunderstorm one is different I guess I’m not done! Lol