Ordered them to be Top/Bottom of each of their respective tiers
some explanations from my personal observation to complement this
Kartana (Top of Tier 2) - Has the ability to benefit from 2 of the current top 3 on the VR, snowballs and Intimidate user are not safe with it's coverage, and supports with TW makes its partners threatening, which can result in opponents splitting hairs on who to target. Frailty is the only thing holding it back from being t1, but is still on the cusp for me.
Kyu-B (Upper Tier 2) - Versatile in what it can accomplish set and EV wise with its stats, and great offensive movepool/sufficient support movepool to play around with. However, is prone to getting worn down due to heavy reliance as a backbone, often being forced to be brought in when SR is up to soak up hits, getting cycled on Intimidate wise if DD or smacked outright with non-Protect sets by Fighting/Fairy coverage users. Still very strong and cannot be ignored.
Zeraora (Bottom Tier 2) - Fastest Fake Out, fastest base speed of the Upper Tier Ranks with a versatile movepool. Useful in almost every matchup is it brought in, as it can be slotted in with the coverage/support you need it to fit (Blaze Kick, Snarl, Knock Off, Close Combat, Taunt etc). Four moveslot syndrome and average bulk, which usually results in an AV set are it's knocks, but is still an excellent support mon that is able to dish out good damage.
Volcanion (Top of Tier 3) - Great glue mon, Fire + Water is cool coverage/backbone (FWG in 2 mons) for any team, and its bulk with items lets it expand a little further into what it can do for a team. However, is usually one-dimensional in its movesets, coverage options carried by a lot of Pokemon can deal with it while often unable to trade due to speed tier, and common Spam like Grass/PsySpam are something it doesn't resist.
Landorus-T (Bottom of Tier 3) - Intimidate, SR, and Pivot with workable movepool. However, Earth Power is usually it's only good attacking move on its moveset, and can often feel lacking or passive as a result; in a battle, I often find it setting SR and cycle it a couple times before it dies. Definitely not as oppresive as it once was, and it having U-Turn + more Speed to work with is the only reason it's not in Tier 4 for me, which is where Scrafty, who does not have pivot, is.
Kommo-o (Top of Tier 4) - Both sets are good, though I prefer the Body Press set for being able to work outside of Misty Terrain while freeing up a moveslot for something like Stealth Rock or Toxic. Requires ample support to get rid of Fairy types (Ghost types if Body Press), is weak to PsySpam, and needs turn(s) to setup, but has enough favorable matchups to be worth considering.
Registeel - (Upper Tier 5) - Another Body Press user, but with a Steel typing and more rounded out bulk. Requires heavy support and play, needing to be paired with Rillaboom and some way to divert (Ally Switch/Follow Me) and removing things like Urshifu-R from the battlefield; putting it on your team means you're saying its the win condition, and its partners are limited to things that will fulfill that.
Regieleki (Bottom Half of Tier 5) - Very matchup fish mon that requires moving around Zeraora/Ground mons if seen, but its KO potential with its Speed Tier against the rest can be downright insane. As much as I'd like to write it off, I still feel the need to add a Ground type or Zeraora to some teams if I spot even one instance of someone using it in a replay because I do not want to lose to a stupid meme.
