Are Gameboy Color games compatible on Pokemon Stadium 1

I was wondering whether Gameboy color games are compatible on Pokemon Stadium 1, or is it only compatible with Pokemon stadium 2.

The English version of Pokemon Stadium 1 (which was actually Pokemon Stadium 2 in Japan) is compatible with the generation 1 games. That would be Red, Blue (Green in Japan), and Yellow. Pokemon Stadium 2 (called Gold and Silver in Japan) is compatible with both the first generation of games, and the second (Gold, Silver and Crystal).

As a side note, the Japanese Pokemon Stadium 1 (sometimes called Pokemon Stadium 0 outside Japan) was only compatible with 42 of the original 151 Pokemon from the first generation.