I'd love to take challenges via Wifi! Sadly, I only get Wifi when I'm home on breaks.
One thing I would like to throw out there is that a lot of the leaders bring their badges back to PAX the next year. This year, there were a few 2010 badges floating around, for example. So, if you missed a particular badge and want a complete set, just ask the leader the next year. I know I'm going to be moving Maylene's team up to Pokemon White so I can accept challengers for the remaining Cobble Badges I still have, even though I plan to cosplay as a different leader next time.