Hm that sounds a little unfair, Ice Climbers attack at the same time, but if Luke were to be balanced in a way that could detach him from Layton then it'd be good :3 I'll look into him more
In all honesty though, by the time SSB4 comes out there will be a lot of characters that didn't make the cut that many of us were hoping for. I remember seeing threads for Geno, Skull Kid, a bunch of Pokemon, etc. when Brawl was waiting to be released. Then it came out and everyone was too floaty, but that's just me complaining.
Anyway, I think a spin off would be a great idea for those characters. There's always a lot of character hopefuls from the Mario series, LoZ, Pokemon and Fire Emblem. I say those four series because they would be the four I'd like to see most and through observation seem to have the most character hopefuls.
Mario already has 4 reps in Smash (if you dont count Yoshi and Wario), so Geno and Mallow, although great characters, I don't think would have a spot. Same goes for Skull Kid, Wolf Link w/ Midna or separate, and a long list of popular Pokemon. Fire Emblem, if Roy does make a return, would keep 3 spots at most IMO. Maybe a fourth for a popular character or villain.
I'm pretty sure I'm not the only one who suggested this, but I'm just trying to be realistic for SSB4.
Speaking of spin offs, Sakurai has to make Melee online. And it wouldn't hurt to give it HD graphics :3
Well look at me rambling at 3 in the morning