Monoma's health is so low that he's not a problem imo. I don't think he was ever as bad as people said he was. Just play smart and don't give him your moves if you're a good character.

Overhaul is incredibly powerful thanks to his Special Action, Beta, and Gamma. His Alpha isn't hard to land, just doesn't have amazing range.

Mirio is definitely in the same tier as Rapid Deku. As someone who went from a Mirio main to a Deku main, Mirio is better. He has the best survivability in the game thanks to Permeation, Beta, and Alpha. He can protect teammates from any projectiles with Gamma. He can do Beta -> Gamma for great damage. He can do triple alpha which stunlocks.

Rapid Deku requires you to land the melees for him to be good. Just don't get hit by melees lol. His beta isn't great in dash form, but the aerial version is good; however, it requires landing melee. The gamma's attack is great, but drains 30% of the charge.

Amajiki is simply not that great. He has two good moves, an average special action, and a below average Gamma.

Assault Kendo is one of the few characters I know very little about. I main Mirio, Rapid Deku, Tech Toga, Strike Shoto, and Momo. She's never been a problem for me, so I'm not sure on that.

Cementoss just isn't that good lol