I'm seeing a lot of contradicting information regarding Pokemon Black and White´s region lock. Some say it IS region locked while others say it´s not. Which is it? Will a EU copy of the game work on a 3DSXL from the US?
Hard to say. Starting with the DSi, all "DSi-enhanced" DS games and 3DS games are normally region-locked.
There are exceptions, though; supposedly, the US versions of Black 2/White 2 are NOT region-locked, while the original Japanese versions are. I haven't really heard whether or not the European version is region-locked.