Here are my problems with the roster, taking into consideration that the final roster is what Gematsu gives us:
1. No heavy weight characters
2. Everyone except Greninja, Pac-Man and arguably Chorus Men are humans or have the appearance of a human
3. No villains
4. Too many obscurities, too little star power
The first point is rather obvious, there's not a single big guy, most of the guys are middle weights with a few light weights. This is a bit of a glaring flaw imo, give us some more gameplay variety.
The second one is where I think it is lacking the most. Villager, Mega Man, Wii Fit Trainer, Rosalina, Mii Fighter, Palutena, Chrom and Shulk are all humans, or in Mega Man's case take on the appearance of a human. Pac-Man and Greninja are the only ones without human proportions, while the only reason I don't put Chorus Men in the human list is because of their face. This simply stinks as it makes it lack in variety, with Brawl we had Dedede, Meta Knight, Diddy Kong, Lucario, Sonic, Wolf, Charizard, Ivysaur, Squirtle, and R.O.B. That's 10/18, that's real variety, 3/12 isn't.
The third one isn't especially major, but it kind of stinks only having good guys here honestly, at least throw in one villain. Melee had Bowser and Ganondorf, Brawl had Wolf and other boss characters in Dedede and Meta Knight. They have gone out of their way to include a good amount of females, now let the bad guys have some fun too.
The last point was inevitable whatever way I see it, but the roster is nowhere near Brawl's amount of star power. Now while it was inevitable that it couldn't match up to Brawl's newcomer roster as there are only so many big Nintendo characters, I think they could have done a much better job on some of the characters. If the Gematsu leak is real the only stars that match up to the majority of Brawl's are Mega Man, Pac-Man and Little Mac, and I guess Mii too, but they're more of an icon than an actual character if you ask me. Palutena, Shulk, Villager and Chrom are sort of middle-ground like Wolf, Ike and Lucario, with Greninja, Rosalina, Wii Fit Trainer and Chorus Men being very out of the left field choices. Here's the thing, this game has 4 odd choices but will likely only have 12 newcomers, Brawl had 18 newcomers with the same amount of oddities. When you cut down on the newcomer amount you have to cut down certain aspects too, and for whatever reason they decided to include just as many oddities at the expense of including less actual all-stars, and that's not right imo. Sure it's fun having an unexpected character in the game, but it shouldn't come at the expense of a character that people are actually cheering for, aka Rosalina over Toad.
With all this in mind, who'd help kick the roster's ass up in gear? I can already see you rolling your eyes, but Ridley and/or K. Rool would do so much for this roster. They fulfill all 4 points here, they'd add so much variety to it it's not even funny. If we had at least gotten one or both of those I wouldn't have a problem, but as it is it has glaring flaws on the variety front imo. And to be honest, not many would have cried over the lack of a Rhythm Heaven rep or Wii Fit Trainer while many would have cheered for Ridley and K. Rool.