There are five generations where new pokemon versions were revealed.

In the first generation of pokemon, Red and Green versions were revealed in Japan on February 27th, 1996. And in October 10th, 1996, Pokemon Blue version was revealed. In September 12th, 1998, Pokemon yellow version was revealed in Japan as an expansion of Red, Green and Blue versions.

In the second generation of pokemon, 100+ new Pokemon were revealed. Also new versions, Pokemon Silver and Gold were revealed on the 21st November, 1999. In Silver and Gold, new legendary pokemon were revealed, such as Ho-Oh, Lugia, Suicune, Entei, and so on. On December 14th, 2000, Crystal version was revealed.

In the third generation of pokemon, the game cartridges were specially made for a new device called the “Game boy advance” which was a slightly newer version of the old Game boy color. The games that were revealed were Pokemon Sapphire and Ruby versions, revealed on 21st November, 2002. It had new a lot of Pokemon. On 16th September, 2004, Emerald version was revealed as a expansion of ruby and sapphire.

In the forth generation, the 3D generation, games had to be played on a device called the “Nintendo DS”, a touch-screen game device. The versions, Pearl and Diamond, revealed on the 28th september, 2007, and an expansion, Platinum version revealed on 13th september, 2007, in Japan. After a while, on 12th september, 2009, Heart Gold and Soul Silver was revealed, as a newer version of silver and gold version, in Generation II.

The fifth generation pokemon was not revealed yet but Gamefreak, the pokemon developer, is thinking of making versions, Black and White. It will be revealed on 18th september, 2010 in Japan.