Yes, the Nintendo 3DS supports local wireless multiplayer and wireless interaction with Nintendo DS, Nintendo DS Lite, and Nintendo DSi system owners.
Can DSi and 3DS download play together?
The single-card download feature in Nintendo DS games will work with any combination of Nintendo DS, DS Lite, or Nintendo DSi system, with the following exceptions: Nintendo 3DS games can only connect between Nintendo 3DS family systems. DSiWare or Nintendo DSi games can only connect between Nintendo DSi systems.
Can DS and 2DS play together?
Yes. The Nintendo 2DS is backward compatible with the Nintendo DS library.