The Dojo needs to be handled better than the way it was for Brawl. The Brawl Dojo was great, but things need to be done differently. For starters, I'd like to see brief video trailers of characters as they're revealed. I really liked this for MvC3 as it was a good way to build up hype without it letting it be prone to exploding in the fan's faces. It also lets us see what the characters are like as screenshots can only say so much.
Video tutorials is a must this time around. Despite being praised as an easier fighter, Smash is surprisingly unintuitive when you think about it.