It depends. If you are creating the game room, you must go into the game yourself, then you go to wherever the multiplayer section is in your game. If you are joining, it depends on the game. In a game like Mario Kart, you must go into the game to join races via Wi-Fi. On other games, you might have to go into the DS Download Play pre-installed app on your DS.
Yes. The 3DS can play DS multiplayer games with any DS.
3DS games do not have friend codes, it is the friend code of the 3DS itself that you use, to be able to play multiplayer on a 3DS game.
Nintendo 3DS games are only playable on Nintendo 3DS systems, and in order to play Nintendo 3DS games multiplayer, you require multiple Nintendo 3DS systems. However, Nintendo DS and DSiWare games that support multiplayer can be played using the Nintendo 3DS system.
Program: YANG
No, the Nintendo DSi and the Nintendo DS cannot DS download 3DS games including Mario Kart 7
You need a SD card to be able to save any additional information for games. Therefore, most of the time and SD card is required. (When you buy a 3DS, it comes with a 2GB SD card) DS/3DS download play does not require an SD card
Yes
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Yes, the 3DS can communicate with other DS systems while playing DS or DSi games or in DS Download Play. However, since the 3DS does not have PictoChat, and no other DS systems can play 3DS software, these features are incompatible.
You play 3DS games on a 3DS, not on a computer.
No, only a 3DS can play 3DS games.
Some people say you have to get a standard ds link machine (whatever that is) but i have a dsi and i tried to play multiplayer with my friend's ds lite and it didn't work.( if anyone can help with that i would appreciate) I have a dsi and i played ds download with my little sister who has a ds lite and it worked fine