About this set:

Base Set is based on Pokémon Red, Blue, and Green, featuring Pokémon from Generation I. The English expansion was released on January 9, 1999, while the Japanese expansion was released on October 20, 1996.

Initially, in the United States, many stores were reluctant to stock the game. As a result, it did not see a widespread release until March or April of that year. Then the 1st Edition print run sold out extremely quickly, making 1st Edition cards some of the most sought-after of all of the early TCG expansions. 

The Shadowless print mirrored the 1st Edition print except for the 1st Edition logo. All cards in the 1st Edition and Shadowless runs were printed with thinner HP and attack text. These cards were without drop shadows for the illustration window, hence the name "shadowless". 

Shadowless cards are equally sought after. The fourth print run mirrored the previous, the first Unlimited run, the only difference being the copyright date, which reads "1999-2000". Fourth print cards were not released in the United States.