the 2ds is basically a 3ds with a single screen and uses 3ds firmware(maybe be diffrences betwween the 3ds and 3ds firmware), NOT an upgraded Dsi.
this means that no r4/acekard/3dsplus etc etc etc will work on it.
Only card that works on 3ds is the Gateway 3DS card.
however, these cards only work on 3ds consoles running firmware 4.5.x and lower.
The starting firmware for the 2ds is 6.3.0-12, this means that the gateway card is not an option as yet...
there may also be diffrences between the 2ds and 3ds firmware which prevents the gateway card running regardless....
in short, no current card will work
disclaimer:
As i do not own a 2ds i am speculating from what i understand of flashcards and what i have read of the new 2ds.
so i may be completely wrong..