Note: this includes everything about a character and how it weighs in in ranked specifically. This includes awakenings, because you can awaken in ranked. 

I can explain any questionable placements in the comments but I'll go over the ones I think people will ask about the most.

Yuta: most people will probably think he's a little low, and he kind of is. I think he has a base kit that's equally good, if not better than Yuji's, but he lags behind because of his mediocre awakening. He is the only character with a domain that isn't tied to the G button that doesn't just auto win as soon as you get the opponent inside of it. Copy is matchup dependant, TLB can only really land if you use the weak version, and elbow rush can be used like 3 times max. With all of this you're looking at taking 1 stock with his ult, MAYBE 2 if you're lucky, while all the characters above him have broken ass ults that will commonly take 2 stocks off the opponent.

Yuki: she may seem low, but lack of ult really hurts her, and if she had a good ult she would be considerably better. Imo she just can't rise above her horrific matchup against Yuji and decently losing matchup against Hakari since they're two of the most common characters in ranked.

Naoya: A lot of people will probably think he deserves to be placed higher, but his biggest problem is that he just doesn't have good damage output. He needs to land the most combos out of any character to actually win the fight, and his moderately increased mobility doesn't really help him enough with that. You can always just dash backwards to deal with most of his gimmicks, and he has no awakening. He's in a pretty bad spot all things considered.

I think the cutoff for viable characters starts at Yuki or Higuruma, which means about half the characters are viable and that's actually a pretty decent amount. 

My personal tier list v1.67.1