EDIT: My last reply didn't make any sense. To simplify it, you need to load up any DS/DSi game on the 3DS (which in your case would be Pokemon) and go to wherever you can change the WiFi settings as you would on a normal DS/DSi and click the red Options box and the last box should be lit up which is the Transfer WFC Settings option. Then you just select DS Download Play on the DS/DSi and click on the box that appears in the Download Play list. I can make a video for you showing how to do it, although it is rather simple to do.