I am planning on getting the eshop version of fire emblem and one of the great features is its streetpass functionality. but i just had a little thought: if someone who purchased the game at retail decided to play a different game, would their 3ds still share streetpass data? it would be a shame if it doesn't. animal crossing is another game that would be better as a digital purchase if that is the case.

The eShop and retail versions are identical. They're the same code, just one is a download and one is on a cartridge. That means the StreetPass data they create and transmit is the same, so they can communicate with each other.

what i meant was when you take out your cartridge, it won't transmit streetpass data just receive them. i could be wrong though, can someone confirm?

I'm pretty sure that if you take the cart. out, the street pass data is still on the system it self (or the Sd card, again not sure.)
so even if you don't have the card in, it will transmit the Game street pass data to the other person, if they have the same game.

I hope that helps, I don't know if I make it more confusing for you. :3

StreetPass data is saved to either the 3DS's internal memory or SD Card memory. You don't need to be playing a game to be able to send/receive StreetPass data. You could even sell a retail 3DS game or (presumably) delete an eShop Retail game from your System Memory, and you'd still be able to send/receive StreetPass data.

cool. thanks for the clarification guys!