yep, that's what it looks like to me, too. It doesn't really make sense to have these attacks just magically appear from your kart, so they added another person per kart.
So basically you pick one person for their driving ability, and they drive, and another for their attacking ability, and they attack. You can switch if you need to, which adds a lot of strategy to the game (so you have to be good with both drivers). And rather than simply attacking in front and behind, you should be able to use the C-stick to attack in any direction. Control stick == driving, C-stick == attacking. Makes perfect sense. It should also make for some amazing battle-mode games.
I just hope they include bots in battle mode.