To my absolute shame I've not played a Pokemon game since Sapphire, which is my all time favorite and most played game.
Watching the Twitch plays Pokemon(if you haven't heard, its 80,000 people playing Red at the same time http://www.twitch.tv/twitchplayspokemon) has got me proper nostalgic. So I'm seriously considering picking up where I left off and playing the rest of the Pokemon games.
Am I best buying a DS or a 3DS to do this? Can you still play DS, Advance and GB games on the 3DS? I assume you can at least download them? If I got a 3DS and Pokemon Diamond, could I trade via wifi with someone on a DS?