I just bought 3ds xl with r4 flash card to play nds with 3ds circle pad. My question is can i play multiplayer games localy with other nds?.. sorry with my complete noobs question..

 

If you can run DS games on the flashcard you can do anything you can with a regular DS game in a 3DS.
So you can play local and Internet multiplayer.
The 3DS has a mode in which it functions just like a DSi, which is actually the only mode flashcards can run in at the moment.
The circle pad does the same thing as the crosspad in this mode.