which Pokemon game should I buy?

Pokemon red, blue, and yellow were all originally made for the original game boy. Pokemon red, blue and yellow were all set in the Kanto region with 151 Pokemon. Also, Pokemon red, blue, and hello each has a slightly different version between them. It's the same way with Pokemon gold, silver, and crystal. Pokemon gold and silver each have a slightly different version of Pokemon, and has different Pokemon because it is set in the Johto region. Pokemon crystal is basically Pokemon gold and silver, but with a few improvements. The story is basically the same. Catch em all! The best game depends on whether you would rather have Kanto or Johto Pokemon.