Because the CT tierlist needs to be buried as much as humanly possible here's a somewhat upgraded version of my previous tierlist, with thoughts below. Unlike before, it's somewhat ordered within the tiers but I don't apologize if the order is nonsense.
A Tier:
B Tier:
C Tier:
With the addition of ordering within the tiers, the top and bottom tiers likely become unnecessary. However, I do feel that there is a bit of a distinction between the top 3 and bottom 5 characters.
A tier represents characters that are really strong.
B tier represents characters that are fine.
C tier represents characters that need help.
B tier was almost impossible to order. I feel that the difference between the top of B and the bottom of B is almost nothing.
Character specific thoughts (super long post follows):
Obviously the most significant change since last time is Falco. I fully admit I was guilty of overrating this character. When you really get down to it, Wolf also has the pillar combo and is better in almost every other way except laser (and he's also significantly faster, which is really important). Even then, Wolf is clearly still beatable.
I feel like Fox, Ivy, Mewtwo top 3 is pretty defensible. Fox is just a constant threat, he's got speed, power, and combos for days. Ivy and Mewtwo are extremely powerful zoners who force you to play the game their way and some characters can't play at all versus them.
Another big mover and shaker is Kirby. Chu has opened my eyes to how ludicrously solid this character is now. Kirbycide aside, he has amazing normals and is easily the best offstage combatant in the entire game. This is quite big in the era of buffed recoveries, Kirby can get the gimps that a lot of other characters struggle to get. He's also got an incredibly solid combo game and a deadly wall of pain. Oh, and he has a great matchup vs Ivysaur because of Sunny Day.
I feel like Marth has fallen off a lot. He used to be the king of range, but many other competitors have appeared that do range better than he does. He also has kind of a unique problem where after a certain amount of damage his combos just don't really work anymore, so he sometimes struggles to get kills that better characters like Fox never have trouble getting, and his defense and recovery are quite bad.
I feel like there's nothing surprising in B tier. A lot of people underrate Luigi, largely because he's very hard to play, but he's quite competent when played well, you really can't underestimate that wavedash and he has an otherwise solid toolset.
I think Samus's biggest problem is that she's a zoner who is significantly outclassed by a few other zoners. Various characters were given tools to deal with the Ivysaurs and Links of the world, which also made them far better at fighting Samus, and as such she just really doesn't feel very threatening anymore. I like the idea behind Ice Beam, but I feel it needs a little more work to really turn her into the goddess of versatility that she wants to be.
Some people have argued that Toon Link is not C tier, and maybe he's not, but the main problem with him is that he lacks any significant benefit over regular Link and has numerous minor drawbacks. I feel like he needs to get buffed in some way so that something he has is clearly much better than what Link has, I'd recommend significantly increasing the range on his grab to be a fair bit further than Link's, so he could be a more throw-oriented character. He still has very powerful throw combos even now, but his horrible throw range makes them hard to land.
I slightly underrated Ganon before. He's bad, but he's not completely unusable. He still hits hard and has some decent combos. He just needs some better approaching options and he'd be okay.
One person I didn't underrate at all way Roy. I thought I had him in B tier before, but he is clearly not B tier. Even with all his buffs, Roy still sucks. The big problem with him is just one of design - since the tip of his sword does no damage, he effectively has significantly lesser range than Marth. This might not seem like bottom tier, but Marth isn't a very solid character, he only manages to be good because he can keep people out with his deadly pokes. Without these, Roy is just a character with mediocre offense and terrible defense. He really needs some kind of buff to his recovery, though I have no idea what it might be.
Ice Climbers are weird. I'm not convinced that they're quite this terrible, yet they just never really feel like a threat anymore. I think they may need damage buffs to their throws and some of their attacks to compensate for the loss of fobble.
I've already made my position clear about G&W and Puff. G&W is just way too slow in pretty much everything that he does, and has weird weaknesses like an atrociously horrible roll and many moves that stay out way too long. Puff just sucks, she's like Kirby minus everything except Fair and Bair. She really needs at least one of Up B or Side B turned into a useful move.