I was just coming to say that Eevee tier fits Kommo-O more than anything - like I said, on some matchups/situations it can be extremely strong, or alternatively it also can be just...useless, and it needs its specific team and is not really easy to use. Will see how it goes in future, though. Will keep using it as it is fun.
As for A rank mons:
A+ -> A. Both of its main attacks received a damage nerf and there are quite a bit more Fairies than there was back in day. Its great for sure, but it requires bit more support than it did for instance like in 2015. Mega Kanga and arguably even MegaGross are easier to slap on teams than this. I would personally probably drop it to A-, but lets take a small steps at once.
A -> A+. Got nerfed; no longer has PuP so it is now very predictable when it comes to what she does, and she is weaker as well. However, she is not really just only nerfed; the Tapu spam and general meta changes made many common Fighting types in 2015 less popular in 2018, and she now has 100 base speed on turn one. Kanga is still extremely splashable and just like always and is probably a best pick when "you need a mega but dont know which one". That IMO just asks for A+. Sure Kanga is not as good as it was but she's still good.
A -> A+. Cress did indeed get a slight nerf with Z-Moves that means that it is now actually possible to OHKO Cresselia without using something absolutely stupid stuff (like CB Megahorn Heracross boosted by HH or something like that). However, I would say she got overall a buff: 50% berries made Cresselia even bigger pain in ass to kill if you dont have a dedicated Z-Move mon to oneshot her. Because of the 50% berries, some Cresselias now tend to run more offensive sets as they can put in more EVs in SpA while still being bulky as shit (even less-bulky Cress wont get oneshotted easily without a Z-Move). There are also some fun tools like Ally Switch to toy around. Also the 50% berries made CM Cress even more aids to fight against than it already was. Basically, she is stupidly versatile with billions of sets and combinations it can run, se is very splashable, is the best TR setter in the meta, in general the best support mon in the meta and forces each team to have at least some form of countering or at least hindering her. With these factor, she certainly asks for A+ if asked from me.
I dont think Aegi deserves S rank. It really isnt worthy to be same tier as the Lando-T, even if the mon is still great and has outstanding features. Its just not Lando-T - Lando-T does its job practically no matter in what team it is and in what situation it is, almost always. Aegi is still slow and thus moves typically last, while its risky in TR as the mon is fragile in blade forme. It also needs knowledge of mindgames with Wide Guard and King Shield to use it in its full potential. It is not that far off from S rank, but I feel like it shouldnt go there.
I also think that Amoonguss could drop to B+, simply because how terrains screw it over and how there are so many mons that can just outright kill it. However, its still the best redirection poke, so I am not 100% certain.