take it out on me
It depends on the event. In some events, there are codes that can be used in multiple regions that can be used on multiple 3DSes and there are other codes that are restricted to specific regions that are one-use. But the region the code was obtained, the region of the game and the region of the 3DS have to match, regardless of your physical location.
Could I use a code from someone else to get Sivally?