Nobody can switch into Chandelure with impunity lol no idea how you could think that, especially with the fact Trick Chandelure has been legal for a while now. Specs Energy Ball always gets a 2hko and even Specs Shadow Ball I am sure would 2hko Milotic unless it was in very high health with high spdef investment (about the same as calm with 56 spdef).
95/79/125 defenses dont scream out amazing to me, amazing in my opinion is something with the defenses of P2 which when uninvested has defenses like 85/145/150 or something similar to that, it becomes much better when invested because of how eviolite works.
I can't actually think of any boosting sweepers Milotic can counter except guys like Scrafty and Suicune who can still own Milotic in a last Pokemon scenario. Sure it can "check" them by (p)hazing them but not without taking at the very least 70% damage and possibly given no healing time.
Plus Victini is going to not be nature locked with Bolt Strike now and that will easily 2hko Milotic no matter what and easily scores a clean OHKO with Band Victini with just SR versus Calm Milotic.
Slowbro has weaknesses to Bug and Dark And Ghost but Milotic can barely counter those guys anyways, not being able to switch into a Sharpedos Crunch or a Heracross' Megahorn sort of sucks. Even Yanmega might win if its specs modest and Milotic is weakened a bit or if Yanmega is LO and gets a lucky flinch.
Yeah and Milotic really has nothing on the heavy hitters physically in UU it for instance with that calm natured set is 2hkod sometimes by Jolly LO Darm's FlareBlitz after SR and leftovers. getting 2hko by a resisted hit is not what I am looking for in a wall. The only Band pokemon it can hope to counter really is azu. Good old LO Ambipom can 2hko Calm Milotic with Return and SR.
Marvel scale is cool but being Toxiced isn't and being burned means you have an even harder time against the likes of PZ and random Houndooms who if they can't KO you (and frankly they proabably will) they will still weaken you t miserable health and only if you happen to outspeed the entirety of your oppoennts team will you be able to recover. you won't.
So yeah idk if you still think Milotic is B rank but the Milotic set that I like to use that I tried out in a research week a couple months ago was a Timid LO attacking tank, was pretty mediocre and relied on surprise heavily.
While I don't have much experience with milotic myself (note to self, really need to make a new team), I did some calculations for SpDef milotic vs specs chandy with a modest nature for chandy's four most used attacks.
Site used was
http://kalashnikov.pokecenter.ru/damage/
252+ SpAtk Chandelure Fire Blast vs 216HP 252+ SpDef Milotic
28-32%
252+ SpAtk Chandelure HP fighting vs 216HP 252+ SpDef Milotic
22-25%
252+ SpAtk Chandelure Energy Ball vs 216HP 252+ SpDef Milotic
49-59%
252+ SpAtk Chandelure Shadow Ball vs 216HP 252+ SpDef Milotic
37-44%
So prior damage or at least 2 layers of entry hazards are required for the 2HKO from shadow ball. As for energy ball, while it's an easy 2HKO, there is a problem, specifically 4MSS. Chandelure has to drop a coverage move for trick, and of all its moves to drop, my thoughts would be losing energy ball, since HP fighting gives perfect neutral coverage with shadow ball alone, as well as a way to put a dent into snorlax. If it does use energy ball...well I guess you're next best hope is that chandy stays in again to use it, while you get a pursuit trapper in.
Banded snorlax with Pursuit, IMO, seems the only remotely plausible counter to chandy anymore, surviving most of its attacks and KOing it with pursuit on the switch, if you're skilled/lucky enough to get that scenario to happen. P2 is almost, if not as greatly hard pressed as milotic to take chandy's attacks, even with maxed out SpDef vs specs, and loses to SubCM (either boosts and FB if flamebody, or PP Stall if flash fire), or requires a very big uphill battle if you use pysch-up for some reason.
But anyway, in regards to the rest of the arguments, my question would be this: Why are you entertaining the idea of using a special tank to block physical hits? I do realise you would normally want a bulky water for fire types these days, but given the rather...questionable...boost to victini, the only water looking good for that job anymore is swampert, unless you can win the prediction war against the choice locked victini.
Looking over the UU pokemon list, I do agree milotic is rather hard pressed to phaze with its sets these days, but if you want to phaze, you really want more than one phazer, preferably one that covers up the weaknesses of the other.
Having anything that can remotely take abuse from chandelure is a pretty good niche to have, as well as take the odd bit of status (although roserade/shaymin should be doing that). Phazing is also useful as at the very least, forcing a pokemon to stop boosting and attack instead does remove the immediate problem of a sweep.
It's not a great wall as a stand-alone, but no pokemon really is. The closest you get with that these days is the gligar/snorlax core, and even that has it's flaws. I think it could be argued B-rank, as it does fill a niche of phazing and blocking chandelure, with support.