To start off with, a roster that would most please everyone would have no cuts from brawl. I figure Snake is likely going to be cut like he should, but I still admit a lot of people wouldn't like that.
Next, it shouldn't have newcomers that aren't that well-liked. Krystal and Ghirahim just aren't that popular and don't really have all that much importance either. They're side characters that if you played only the best games in their respective IPs, you might not even know them. --- Palutena, Isaac, Ridley, King K. Rool for SSB for Wii U and SSB for 3DS!
Saying that it would please most people is guaranteed for people to come in and crap all over it, but it Sakurai released this as the final roster people would be tripping over themselves to gush over how much they love it.
I would be happy with this roster, anyway. --- "Mephsuit, as he so often is, is right." - Token sane 261 member Saber_Tiger a.k.a. SST
I think there's one roster that would please most everyone.
He did say most everyone, not everyone. Not everyone is going to be happy no matter what, but cuts would hurt less than not getting newer characters that people want or like. --- Look In my Eyes! What do ya see!!
Some people want no cuts. Some people don't want various characters (Snake seems to be most common) returning.
Some people want Chrom. Some people want Robin. Some people want Lucina. Some people want some combination of those, or a different, fan-favorite-but-not-plot-important character (Owain, Tharja, etc.). Some people want Marth, an Awakening rep, and Ike. Some people just want the first two. But almost no one doesn't want an Awakening rep, so leaving one out isn't an option to please everyone either.
Some newcomers are so polarizing (K. Rool, Palutena, Ghirahim, Mii) that including them will anger just as many people as leaving them out will.