Sure, you can challenge the computer, but like all fighting games Super Street Fighter IV is more entertaining when you’re fighting against other players. Capcom made sure there are plenty of ways to do find a challenger in Super Street Fighter IV 3D and this trailer from Nintendo World showcases all of them.
When you want to fight a friend (or stranger) on a subway train, you can make use of Super Street Fighter IV 3D’s local lobbies. Before a match begins you can set options like the number of rounds, time limit, and canned comments. Super Street Fighter IV 3D supports download play so you only need one cartridge for local versus play.
Nearby a router? Then you can select "Internet Versus" for online matches. Players can opt for a quick match if they aren’t concerned about match conditions or custom match if they want specific settings. Custom match lets players chose the number of rounds, time, area, opponent strength, and control type. Super Street Fighter IV 3D has worldwide online play so I believe area is for the location of another player.
Capcom makes a vague mention of using friend codes to construct a friend list that keeps track of challengers you fought locally and over the Internet. You can use this list to set up rematches over the Internet with ease. The Channel Live feature allows players to watch online matches as they’re happening.
Just like the console version, Super Street Fighter IV 3D keeps track of battle points (BP). Local and online matches can contribute to a player’s total BP. The arcade challenge feature where an opponent can jump into your single player game is in Super Street Fighter IV 3D too. On Nintendo 3DS, challengers can "enter the ring" via the Internet or over a local wireless connection.
Super Street Fighter IV 3D also has a crosspass mini-game where figures fight when you pass another player on the street. Figures are procured from a slot machine style mini-game or from trading with other players. While this feature may not get much use in North America outside of major cities and perhaps college campuses, thanks to Dragon Quest IX crosspass features are quite popular in Japan.
We have hands-on impressions of Super Street Fighter IV 3D from Nintendo World so check back for those soon-ish.