I wanted to train up a few Scatterbug that I had traded for, so I put my regular team in the Battle Box, thinking that if I were challenged to a battle, I'd get to pick to use them instead.
So of course, I was challenged to a battle. I accepted, and when I got to the screen where I could pick which Pokemon are entered, I only saw what was currently in my party, and no option to get my Pokemon from the Battle Box.
Is this what the Battle Box is used for? Why couldn't I battle with the Pokemon in it?
Best Answer
The battle box can only be used in in infrared link battles, the Battle Subway, Random Matchup and Tournaments which utilize the "Battle Competition".
source: http://bulbapedia.bulbagarden.net/wiki/Pok%C3%A9mon_Storage_System
Try doing a inferred link battle and see if you can use the battle box.