Kid Icarus Uprising will include an adversarial multiplayer mode. The footage shown during Nintendo's E3 press conference featured several knight-like characters duking it out in traditional deathmatch multiplayer. According to Nintendo president Reggie Fils-Aime, players will be able to challenge one another in 3-on-3 matches.
Fils-Aime also mentioned Kid Icarus themed AR cards. When placed next to one another, in-game character models spring to life and start doing battle. It's unclear exactly how this will function, though the implications for future Pokemon trading card games is kind of frightening.