If Wario's trophy description is any indication, they kept his Brawl moveset. All I needed to know!
Now just officially confirm him I need to see him in action ;_;
I'm wondering why they couldn't clone Fox and Ness for Wolf and Lucas, respectively. That would've satisfied those who used them a lot in Brawl, whereas Dark Pit doesn't have an established SSB fan base yet and Dr. Mario has already been cut before. Oh well, there's still a chance they'll return. We can hope. :(
Because Lucas and Wolf really aren't clones, they're just designed with the concept of an existing characters. All their moves, animations, properties etc are all different. Lucas only shares 2 animations with Ness. (FSmash and Up B)
With that in mind, they take as much time as any other veteran that isn't a clone. Doc, Lucina and Dark Pit, on the other hand, are very easy to add and take absolutely no time because the work is already there. We know Lucina has the exact same animations as Marth, and Doctor Mario was the same in Melee so he'll probably share animations with Mario again (except for Down B HOPEFULLY). Dark Pit, going off his placement on the select screen, will probably be the same as them. The only thing needed is unique taunts, idle and victory animations, changed moves properties and new voice lines. (Which is especially easy for Doc and Dark Pit because they share voice actors from the characters they're cloned from.)
I'm assuming the reason they cut Wolf and Lucas, despite being unique all things considered, is because they're redundant. As mentioned, they're designed upon an existing concept, so to a lot of people, they're really repetitive. Ice Climbers are tricky, and honestly, hard to design. In Melee they had some pretty broken techniques, which weren't fixed in Brawl. Nevermind the design problems hey have on the 3DS, they're just poorly designed in general. I don't think that's the only reasons they were cut, but time constraints was probably a problem. Sakurai mentioned that Lucina moved up from being an alt because they had to cut a character mid-development, so she was only there to pad the roster, and I'm assuming Doc and Dark Pit got the same treatment because two other cuts happened. 3 clones made up for 3 cut veterans. I'm assuming Snake (THIS IS BULL AND INEXCUSABLE), Squirtle and Ivysaur were planned to be cut from the beginning.
TL:DR: It's either Lucina, Doc and Dark Pit or nothing at all. The former is the winning option.