After watching the big stream from a girl named Gema, I saw a lot of Ness footage (actually looks quite buffed!). I didn't notice what his custom moves were, but I'd guess that he'll have the option to switch to Lucas' Specials. Sad to say it, but I think Lucas is as good as gone.
The footage that I watched was quite long, it was basically this girl unlocking all of the characters through Classic Mode. After R.O.B was finally unlocked (believed by many to be the last character), she got a message in which she translated as something along the lines of "Congratulations! You have unlocked all usable fighters! Let the real battle begin!".
In other words, the leak was dead-on and the only way we'll get any new characters is DLC at this point, as there ARE still four slots that could be filled by characters in the bottom, but that's it.
Honestly, I'm a bit salty that they kicked Lucas to the curb, and fill slots with characters like Dark Pit (saw footage of him, too, and he has absolutely no changes from Pit) and Dr. Mario (does have subtle changes from Mario). I don't mind them, but to me it means that characters like Wolf and Lucas should not have been cut.
To think a year ago I kind of thought Porky or another EB rep could even sneak in somehow, but I seriously doubt it now.