To be honest I'd only go by Black & White 1 here.
I had a EU copy of Black and sold it to get a US copy. Few reasons why I believe (hope) these games will be region free is after looking around a bit, apparently AU, EU and US copies of the game lacked region coding and were all bit-for-bit identical and thus, they worked on all DSi and (I think) 3DS systems (including the Japanese consoles). All EU English Pokemon were also classed as US Pokemon and the US games also lacked the ESRB rating that normally appeared at the start of all US Pokémon games on the DS.
The game IDs on the box were also identical across all the regions except for Korea and Japan (TWL-IRBO for all Australian, European and American games with the USA, EUR, AUS tags added to whatever region you bought the game from / in, where normally it's either E or P replacing where the "O" letter goes with E for American and P for European). The method they used to localise the games also changed (which is why the games were released simultaneously) and NoA and NoE staff were both included in the credits roll.
Conquest is sort of different though. US copies also didn't have region coding but were not loading when it came to Japanese and European DSi console (probably Japanese 3DS consoles as well) and even the AU games, which are supposedly under "European rule" didn't work on other EU consoles though that and US copies worked on UK and other European 3DS consoles. UK Conquest games are fully region locked though, as they have the region coding other DSi games have had.
I'd say what happened with BW1 has a could happen with BW2 but I think it's better to wait till the the games come out everywhere (in two weeks) and see what's up cause there is also a chance all of what I said is wrong or they changed things.
