Pokemon Sapphire
My nine year old had pretty much completed Pokemon Pearl on his Nintendo DS (with the help of cheats) and wanted more. He tried a friend's Pokemon Platinum and found it was too similar. We bought the old Pokemon Sapphire for Game Boy Advance which is completly compatable with the DS. He really likes it even though the graphics are not quite as advanced. He would definately recommend it for someone like him who needs more Pokemon. (Ugh!)