Super Street Fighter IV 3D's StreetPass functionality has collected "figurines" fight each other whenever two people with the game pass each other within local wireless communication distance. In his recent investor briefing, Nintendo president Satoru Iwata described the StreetPass integration of another 3DS fighter, Dead or Alive: Dimensions, and it's a bit more hands-on.
"In Tecmo Koei's Dead or Alive: Dimensions," Iwata said (according to Nintendo's translation), "the character parameters, which shall be determined by a player's play pattern, shall be exchanged and, as the result, you will receive a challenge from the character, [Tecmo Koei says]." If we're reading Iwata's description accurately, the game will determine your play-style over time, and then broadcast an AI character based on these patterns over StreetPass to challenge other players.
