While Kid Icarus Uprising will come with six AR cards, each box does not have the same six. Some people like myself will probably not touch them past what is necessary to include in the review (the ones that came with my 3DS are still in their sleeve, in the box, sitting on a shelf back at home). Some people will probably make it their goal to collect all of them, but how, short of stealing them from your friends?
Well, if you live in Japan, just buy Choco Snacks! They bear rather striking resemblance to the Cocoa Puffs many of us know and love, but each ¥100 pack will contain one of 20 AR cards.
Sadly, there's no word on them being sold to the US, so you may have to import some and pray they're not too stale one they arrive. Still, forget the AR cards, I just want some of these Choco Snacks.