Nintendo detailed the Kid Icarus: Uprising multiplayer modes at today's Nintendo Direct presentation. The modes include an all-out battle royale, and a multiplayer mode more similar to VIP modes in various shooters.
"Light vs Dark" is a team-based battle and VIP mode, in which each team drains the other team's health meter. The last defeated team member when the bar is drained becomes an angel, and whichever team defeats the opposing angel wins. The game also has a "Free-for-All" mode, in which six players combat each other directly -- akin to a standard Deathmatch mode. The six players can include CPU opponents, so you can still play if you don't have five friends. Both modes are available to play through local wireless or online.
You'll also be able to use weapons that you've unlocked in the single-player mode in multiplayer. You can customize your own character with weapon and power combos to fit your play style, and you can fuse weapons at the Arms Altar. The StreetPass functionality comes into play by sharing "Weapon Gems." These represent the weapons of players you've encountered, and you can purchase them for yourself by paying with hearts. You can also fuse Weapon Gems together.
Kid Icarus: Uprising is set to hit March 23 for $39.99.