Some impressions after my time playing. Most of them are after tons of matches on for Glory vsing these characters:
The top 5 I think are Sheik, ZSS, Rosalina, Greninja, Diddy in that order. Sheik is, by far and away, the most used online [People say Mac, but he's rare compared to Sheik]. Sheik has great projectiles, legitimate combos, especially with tilts and throws, very fast, great specials, and she can pull off kills a bit earlier with her aerials. She absolutely can't kill on the ground though, that's her only flaw.
ZSS is essentially like Sheik, very very overused online, 2nd to Sheik. She's also fast, good range, has troubles killing and her grab is ok. I see her as a very very slightly worse Sheik in most matters.
Rosalina's luma is very annoying, able to control most of the stage if used properly. A relatively high skill curb to master, but deadly. She's still a high tier even without the luma. I think her biggest flaw though is her gigantic size and light weight though, very susceptible to being killed early if you can pressure her when she loses Luma, while not being hard to do so thanks to her size. She's decently fast too, but not to the same level as ZSS or Sheik.
Greninja when I first tried everyone out felt the most fluent and easy to use. He feels like a Melee character in this. Great projectile, throws usually go into combos, grab range might be slightly bigger than most i'm not sure...he does struggle to kill though. Moreso than the others listed above.
Diddy may have lost 1 banana, but I felt that his normals were buffed immensely in terms of speed. Other than that, same old Diddy. Bananas are still deadly. His attacks being buffed all around to helps a lot. Still can't kill great though and his recovery can be gimped.
Lucario looks like a solid #6 to me, those aura mechanics are just plain scary in this game added with the rage effect. But all his moves feel like they need to be much more precise in this game than the last. I don't like playing him much this time around. Doesn't change that aura is insane though. He's be mid tier if he only had the aura effects from brawl
Sonic seems like #7 to me. He looks as if he can actually combo with his spin dashes this time around with more priority attacks. I hate his playstyle, but it works in this game.
Then we got high tiers. where I think Falcon , Duck Hunt, Bowser, Robin, and Mac will lie. Falcon is back to his Melee glory days, pretty much identical to his Melee counterpart, except he's easier to control. My favorite Falcon in Smash Bros yet. Mac is very polarizing, but I'm in the portion that believes he will stay strong through his stay. Super armor smashes are ridiculous, and he kills a lot earlier than most in a game with increased blast zones. He may fluctuate in the high tier, but he will stay there. Duck Hunt still has crazy projectiles, but not a great anything else. He shuts out Bowser very, very hardcore though. Duck Hunt could stand to be a bit faster though. Bowser is also a high tier thanks to numerous speed buffs and able to kill earlier than most in a game where everyone got nerfed killing power. Absolutely shut down by projectiles though, see Duck Hunt.
I could see Meta Knight hovering around the high-middle of the mid tier range. He does feel pretty bad compared to Brawl Meta Knight, of course. He's pretty bad at everything but racking damage and offstage game, which is still great. Other than that, really bad. But his offstage game is super strong still, and his moves rack damage well.
Robin has a well balanced game of range and power. His projectiles are versatile like Thunder, Elwind for spikes and recovery, and arcfire for grabs and landing moves. Also his Levin sword is STRONG. You can kill around 90% with it in the air and ground with smash attacks surprisingly. He’s a bit on the slow side though, his nosferatu is a bit under par [distant nosferatu looks great though] and although I don’t see see elwind spam being a problem, it can happen, leaving Robin with no recovery during crucial moments. Someone who can exploit making Robin using his resources up though would be the reason Robin drops lower on the tier list.
Game and Watch is worse than his Brawl counterpart. I think he’s a middle tier better than Mario and Luigi, but not by much. He feels fasters overall, but I find it tough to pull off kills with him this time around. He was also a secondary of mine in Brawl. His aerials feel overall better though. D tilt is weaker, Grab game is weaker. Not like he changed much otherwise, but he does feel worse than his Brawl half.
Middle of the middle tier looks like Mario, then Luigi, then a few other characters, and Doc take the very bottom of the mid in this game. Mario takes the edge over Luigi in this one thanks to the [slightly] better D throw than Luigi and overall speed. I mean, if Mario grabs you at 0% you are guaranteed 40% and there is nothing you can do about it. Fludd seems a bit more useful this time around too. He feels very fluent in this one, and fair lands more consistently this time around.
And Luigi my main...still don't see why people are calling him low. He lost KO ability yes, his recovery isn't great either [usable, but not great. Better than recoveries such as Marth though] but his D throw is massively improved, so many leadups from it [Combos from 50+ if you get lucky with Dair spikes...sometimes. potentially better combos that Mario with the D throw but too situational]. His ground speed is a little better, his fireballs are definitely faster and usable now. Not great, but usable. His very slow in the air and easy to juggle though. Tornado is massively buffed as a kill move. It's not great for recovery [unless you use tornado 2, but then you lose it's awesome attacking prowess]. But yeah, great approaching, few moves stop a falling tornado. Heck, very few expect a rising one off the ground. If you're anything over 100% near the top of the screen and hit with the tornado, you're dead. Dair in general is faster and the spike is about 50% more likely now. I’ve scored numerous kills landing this offstage and it sets up basically any move you want if you hit the spike. Even up Bs in the air. Uppercut is weaker...but less punishment if you miss, at least. Missile sucks. Reduced to 1/10 misfire, but I think the actual misfire may be better. Use any custom over this please. Overall though he is Brawl Luigi with a better combo game and projectile in trade for killing and recovery [both which he can still do average]. He's an average character, which makes him a MIDDLE TIER. Just slightly worse than Mario due to a speed disadvantage.
Doc. Now here's the guy I think people are overrating. He's the one who I think could be low tier at the drop of a hat, as soon as I play with more characters extensively. He feels horribly sluggish compared to Mario, his D throw does not combo nearly as well, his tornado is a laughable distance for recovery and inferior to Luigi's tornado in almost all aspects, and I think Mario's dair is better than Docs. Also Mario's fair not being able to spike is saddening. Although he can kill better than Mario and his pills are a hair better...he's not great compared to Mario, or Luigi. I expected him to be better than Mario initially. I was wrong.
Low tiers are looking like maybe Doc, WFT, Ike, Olimar, and Palutena in that order to me. WFT has the most potential out of all these characters though. I just haven’t seen it yet. I would probably be convinced after playing a good WFT, but I still can’t stand those awkward hitboxes and killing power being reliant on deep breathing which is hard to pull off while being pressured. Soccer ball isn’t a great projectile either and difficult to hit with [I know about the giant ball custom, I’m going off of normal moves]. I did learn it was a meteor smash up close today though…She’s also pretty fluent movement wise. I do see potential for middle tier for sure with WFT, but I have to see good WFT players first. Maybe I’ll go look at Youtube.
Ike is just inferior to his Brawl counterpart when Killing was about all he had along with his range. Without that kill power…he feels like half a man. Everything else is still there for the most part though, exactly the same. He was a low mid before and now he’s a top low now.
Olimar is just flatout worse than his Brawl counterpart. Losing those 3 Pikmin were a major, major hit. He was my secondary in Brawl, I just can’t play him now. His Pikmin feel less durable now [Yes, I know about his custom again], and they run out far quicker with only 3 in tow. The order is nice sure, but I just really don’t like him here. His recovery is pretty easy to intercept too. Could be worse than Palutena.
Palutena for the reasons listed by everyone basically. Horribly slow tilts, horrible default specials, nothing else special aside from grab game and a great u smash. I’m sure she’s better with customs but I don’t look at customs.
Everyone else I haven’t looked into enough or seen enough. Shulk has potential though. Also I tend to have better experience with boxer/up close characters. I hate zoners, which is why I dropped Duck Hunt...anyways,I don’t think anyone is unusable in this game at all, nor do I see any bottom tiers.