Street pass collecting 3DS:
Go to the Nintendo e shop and find steel diver sub wars download it.
When you enter it there will be an internet battle option go into this.
There will be 2 options displayed, Random battle and Matched skills battle go into either one of these.
When the game loads people will enter the room when its full turn off your wireless connections and those people will be added to your street pass MII plaza if your spot pass is on for MII plaza.