Traders and collectors might find this guide useful. Here are images of 4 base set cards. All are different. Collectors refer to these cards as 1st edition, shadowless, unlimited, and 4th printing. Here is how you can tell them apart:
This is a 1st edition Base Set card:
This is kind of a no brainer. Look for the 1st edition symbol.
All 1st edition Base Set cards are shadowless. See the right side of the caricature on the card? No shadow.
This is a Shadowless Base Set card:
This card is exactly the same as the 1st edition card minus the 1st edition symbol. Note there is still no shadow to the right of the image.
This is a 3rd printing (Unlimited) Base Set card:
This is the first printing of "Shadowed" cards, see the right of the image.
Note the fine print at the bottom. "1995, 96, 98 Nintendo, Creatures, GAMEFREAK, 1999 Wizards."
This is a 4th printing Base Set card:
Still a "Shadowed" card.
Note the fine print at the bottom. "1995, 96, 98 Nintendo, Creatures, GAMEFREAK, 1999-2000 Wizards."
Hope this little guide helps clears up any confusion.