I would imagine that the Box acts as a slow-moving, mobile form of defense, like the shields. He'll still be able to use a regular shield, like the rest of the characters, but the Box will act sort of like Fox's Reflector attack, or Ness' PSI Magnet. Maybe it'll just cut damage down to half, instead of blocking all damage like the shields do.

Yeah, Zero Suit Samus looks fucking badass. I'm thinking they're probably going to make her a more up-close character, as opposed to Power Suit Samus, who relies almost entirely on ranged attacks. Maybe they'll do something like they did with Zelda, where the two characters are actually rolled into one, so you can switch between them in mid-fight.