Pokemon Chaos Black is FAKE! DO NOT BUY UNDER ANY CIRCUMSTANCES. This was never and will never be an official Nintendo game. Other faked games are Pokemon Jade, Quartz, Naranja, Perla, and some more.

Complete List of every Pokemon Game made officially by Nintendo to date: (25th August 2007)

Pokemon Red           Larger GameBoy Cartridge, Red coloured, Sticker on front with picture of Charizard
Pokemon Blue          Larger GameBoy Cartridge, Blue coloured, Sticker on front with picture of Blastoise
Pokemon Yellow       Larger GameBoy Cartridge, Yellow coloured, Sticker on front with picture of Pikachu
Pokemon Silver        Larger GameBoy Color Cartridge, Silver sparkly coloured, sticker on front with picture of Lugia
Pokemon Gold         Larger GameBoy Color Cartridge, Gold sparkly coloured, sticker on front with picture of Ho-Oh
Pokemon Crystal      Larger GameBoy Color Cartridge, bluey-see through coloured, sticker on front with picture of Suicune
Pokemon Sapphire    Smaller GameBoy Advance cartridge, blue see through coloured, shiny blue sticker with 'Pokemon Sapphire Version' written on it.
Pokemon Ruby         Smaller GameBoy Advance cartridge, red see through coloured, shiny red sticker with 'Pokemon Ruby Version' written on it.
Pokemon Emerald     Smaller GameBoy Advance Cartridge, green see through coloured, shiny green sticker with 'Pokemon Emerald Version' written on it.
Pokemon FireRed      Smaller GameBoy Advance Cartridge, red coloured, shiny red sticker with 'Pokemon FireRed Version' written on the front.
Pokemon LeafGreen  Smaller GameBoy Advance Cartridge, green coloured, shiny green sticker with 'Pokemon LeafGreen Version' written on the front.
Pokemon Diamond    Much smaller, flat DS Game Card, Gray Coloured, sticker on the front saying 'Pokemon Diamond Version'
Pokemon Pearl         Much smaller, flat DS Game Card, Gray Coloured, sticker on the front saying 'Pokemon Pearl Version'

These are the main games, most likely the ones you've been asked for / are looking for. Other Pokemon games you may encounter are covered below.

For any of the above games, (excluding the DS games) the cartridges are NOT GREY. Don't buy if the cartridge is grey.

Note: If you don't know what a 'Blastoise' look like, punch it into google images and you'll soon find out.

List of other Pokemon Games:

Pokemon Snap (Nintendo 64) Large cartridge, coloured sticker on front.
Pokemon Stadium (Nintendo 64) Large Cartridge, coloured sticker on front.
Pokemon Stadium 2 (Nintendo 64) As above.
Pokemon Pinball (GameBoy) Game Boy Color Cartridge, with large battery case attached. Yellow sticker.
Pokemon Trading Card Game (GameBoy) Black/dark grey casing, sticker with Pokeball on the front.
Pokemon Puzzle League (Nintendo 64) - Large Cartridge, coloured sticker.
Pokemon Puzzle Challenge (GameBoy Color) Gameboy Colour cartridge, coloured sticker.
Pokemon Pinball Ruby and Sapphire (GameBoy Advance) Small, Gameboy Advance cartridge. Blue and Red sticker.
Pokemon Box Ruby and Sapphire (Nintendo GameCube) This one's tricky. Only given away with Pokemon Colosseum, don't be surprised to see this bundled with it. If on it's own, it's a minidisc with Blue and Red on the sticker.
Pokemon Channel (Nintendo GameCube) Minidisc, clear writing.
Pokemon Dash (Nintendo DS) Grey DS cartridge, green and blue sticker.
Pokemon XD Gale of Darkness (Nintendo GameCube) Minidisc, clear writing.
Pokemon Colosseum (Nintendo GameCube) Minidisc, clear writing.
Pokemon Trozei/Link (Nintendo DS) (Trozei is American) Small DS cartridge, yellow and white sticker.
Pokemon Mystery Dungeon Red (GameBoy Advance) Grey cartridge, red sticker.
Pokemon Mystery Dungeon Blue (Nintendo DS) Small grey cartridge, Blue sticker.
Pokemon Ranger (Nintendo DS) Small grey cartridge, sticker with oval shaped logo.

Pokemon green is not a fake but it is Japanese. It has a picture of a Venusaur on the front of the cartridge. Be warned that all the writing will be in Japanese, and will not be changeable to English or any other language.

Any type of Pokemon game on the PC is fake, Pokemon games have only come out on the Nintendo GameBoy, GameBoy Color, GameBoy Advance, Nintendo DS, Nintendo 64 and Nintendo GameCube. There are PC Emulators, but I would suggest steering clear.

Ignore 2 in 1 games, those are fake. Nintendo has never released any 2 in 1 Pokemon games.

Tricks and Tips

Ask whoever you are buying it for whether the game you are looking at is real or not. So, if you have a son who wants 'Pokemon Ruby' show him the game picture and ask if it is real or not. Better to let him find out what he is getting for Christmas than to buy a fake game that doesn't work, and he gets upset.

If the game is 'brand new unopened' but not factory sealed, why? Who rips off the factory sealing just to sell it on Ebay? Be aware of those sort of games.

If you are in any sort of doubt about buying it, don't.

Ask the seller questions about it, if they are withholding information, it's best not to buy.

There are so many different people selling the same game, don't hesitate to keep looking.
That is about everything, feel free to email me with questions.

Thanks for reading, and I hope it will keep many a Pokemon Fan from getting upset!