Considering the Ice Climber-esque blizzard, the new Hammer Flip, and that Final Smash that's 10x as better as his old one, I think he's going up on the tier list significantly.
Well, the "blizzard" will be a custom move, so we dont exactly know if that will even be tourney legal, maybe a side event. And Final Smashes are definitely not gonna be in there, and hammer flip is sooo slow and telegraphed... hitting with that will be even more difficult than before. So, Kirby might be better, but not because of those reasons. His specials were always pretty situational.
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To the OP, Kirby will be much better if there is hitstun. A person who studied Kirby's combo potential in Brawl, if there was just a little more hitstun he could 0-70 almost everyone... so assuming everything has the same combo potential and there is hitstun, hed probably fall high-mid because of that alone.
If they made inhale safer that would also help him. Everyone hoping for the Cutter Dash, keep hoping, it wont happen. I still hope Kirby can hammer cancel, and quick rock tho. I also wonder if Kirby's dash attack will be different (one weve never seen before, not PM or Melee's dash attack). It would also be nice if they made all the copy abilities all viable. From what Ive seen so far.
I kinda know which ones will be the best... Little Mac's will be one of the best if somehow Kirby could get the OHKO from it. Villagers will be better in doubles, but still good if the opponent insists on spamming Side-B projectiles or something. Megaman's will be one of the best. WFT's is also pretty good. Same with Greninja's. Pit's still good, but not as good as it was. All projectile ones will be above average. Ike's still looks bad, same with Bowser... but we'll have to wait and see.
So for Kirby to be good, some things would have to happen. Increased hitstun, safer inhale, similar combo ability from Brawl. And to make him top tier, he would need better aerials, more air speed, u-throw kill move, and d-throw combo move. Thats basically it.