I just realised that since I have a second 3DS I can use it to StreetPass with my first one. Which I have done so and seen the Mii in the plaza etc.
But I'm not seeing anything in Pokemon Shuffle. I believe you're supposed to gain extra hearts but I'm not getting any. The StreetPass option in the settings is turned on. Do I need to do something else to register SPs in Shuffle?
If StreetPass is enabled and not working it's time to debug. Here are the steps I would take.
That's all I got for now.
Are you not seeing your second 3DS/other people streetpass listed at all under the Streetpass profile thing where it shows you statistics and stuff?
For one thing, you only gain hearts via a certain number of people you have streetpassed, not every one.
Edit: You only gain hearts every tenth streetpass after first and second; full chart here.