Hmm. Unlike BW, this game has region coding:
NTR-VPYP-EUR
The strange thing I found was that the American and Australian release had no region coding:
NTR-VPYT-???? [Blank]
Yet it didn't function on any foreign DSi (even the Japanese console). Even the Australian game was region locked when attempting to play this on a PAL DSi, yet you could play this on a foreign 3DS without issue and the DSi enhanced features would work (whatever they are), so these games weren't region locked fully, but if you ever wanted to play these games on a DSi (which is better for DS games), you were out of luck.
This game, however, wasn't developed by Game Freak, so Black & White 2 could very be region free (I hope, PAL game cases are horrendous) like BW1 as the release dates are so close together so why not just give everyone the same card. 3DS interaction will likely not mean anything as the Dream Radar could very well be language locked like Pokemon Battle Revolution, where you could import Pokemon from a US game Gen IV onto the PAL copy of PBR without issue and the same (I think) for the Pokeshifter. It's also cheaper to distribute without a region as then you don't go through the trouble of having to producing 2-3 SKUs, which is likely what happened with the US and Australian copies of Conquest (and what definitely happened with BW1).