The only outlier is literally Doffy and his strings but he has narrative backing to not even downscale due to being directly stated below 2 "YC3" in Jack (Kaido called him strong and Doffy weak) and Cracker (Big Mom sent him to deal with Luffy even after knowing he beat up Doffy) while the rest of them don't.
Doflamingo himself its physically inferior Jack and Cracker, however its his Strings which matter here, as they consistenly display far greater tougher than Doffy himself, his Strings do legit scale to Jozu's Durability/Lifting Strength.
As even after Marineford, in Dressrosa (prior of Gear 4th) his strings where show to be virtually indestructible against most, they could even tank Gear 3rd blows, where Doffy himself (despite having physical superior) could still get injured by Gear 2nd Luffy. The Birdcage itself couldn't be either stopped or damaged, with characters like Zoro and Kin’emon capable only to slow it down.
To remind you, Kin’emon was one of the four Nine Red Scabbards which that actually make Zoan Kaido bleed (but not actually damage him) with a combo attack, and while i don't think that definitely put him above Boundman (since it was a collective attack), its still worth feat, not to mention him be comparable to Ashura Doji, Nekomamushi, and Inuarashi who fought on par with Jack.
And while Fujitora wasn't going all out, the fact that his casual level of strength couldn't break the Birdcage (either with his meteors or when he start using his Haki against the strings) do further validate the scaling, as again prior of them the only characters who could actually withstand casual attacks from Admirals where people like Jozu, Vista and Ace.
The only issue would be the Black Knight be able to be shatter by Gear 2nd Luffy as well as be damaged by weaker foes, however i do feel like the Black Knight its meant to be that strong as its suppost to work as distraction or trick the enemy into believing they where facing the true Doflamingo, and that the reason why he could maintain that technique for long period of time its because the strings where weaker making it less stamina consuming.
Which its plausible as other moves like Overheat he can alter the proprieties of the strings, making them hotter, so its more than likely that he can also alter their density/durability, making them weaker when using Black Knight or stronger when using Parasite, Birdcage or other more combat oriented techniques.
If you want to, you can say that Vista and Marco don't really scale to the admirals (and thus the top tiers) due their failled attempts to fight Akainu who is relative to Kuzan, and then only Ace and maybe Jozu still scales with the Marine ford scaling chain being something like: Vista and Marco<<akainu=Kuzan~>Tortured Ace and Jozu.
I don't include Marco with them as unlike the other, he does have actual feats and statements that could put him at fully Low 5-B (which i feel should only be fully applied to what people usually refer to Top Commander+ Tier like Onigashima/Post Wano Kidd, Onigashima/Post Wano Law, Zoan Forms Yamato, Post ACoC Zoro and Post ACoC Base Luffy, Awakening Form Lucci).
From the Gorosei believing him be one of the few people who could potentially stop Blackbeard along side the Emperors, him able to briefly match Big Mom with her admitting that she would have needed all her Homies to fight him, or him actually able to outmatch/outspeed both King and Queen at the same time before losing due of Stamina.
On the Boundman stuf, Big Mom using Haki does not mean she needed it. She uses whenever she feels like it (plot makes her stupid you've read the raid)
The true stupid moment started only during the raid, before that and especially in Whole Cake she hasn't show the same degree of PIS moments. Beside that if Big Mom didn't need Armament Haki to clash with Boundman why she would have done it in the first place?
Like she may be far from be the smartest person but i doubt she its the type to put effort when not necessary, she does have Observation Haki and she know when someone its actually a genuine threat or not (like how she warned Kaido to avoid Zoro's Emna attack), so there are to be a reason why she choose to use Armament Haki where she could have just use her natural durability/strength.
and only makes both be weaker than no homies Big Mom and thus making those forms and those who scale to them weaker than Base Kaido and Big Mom, but when both are manhandling higher tier commanders when serious like Big Mom did Marco
Like i say i do think Marco its the exception as he actually had a far more solid case of him fully scale to Low 5-B due of the previously mention feats and statements, as well as general potrayal.
So her needing the Homies to actually defeat Marco isn't an issue, especially when this its the same guy who could outmatch both King and Queen at the same time, where Zoan Queen himself was getting tossed around by an even weaker Big Mom who lost her memories, didn't have her Homies and didn't see to be able to properly use Haki (or at least against Queen she didn't need it to ovepower him).
and it can also easily be viewed as suspicious
just wanted to share that with you guys real quick 
hopefully the journey won’t be annoying tho 
