Joker5000

Haumea mind controls him. If he somehow gets past her he dies to Dragon. Also why is Dragon below Charon?

Sukuna stomps. Muzan can’t kill him and Sukuna has seriously injured Mahito who only takes damage if you hit his soul and Muzan has no defense against that.

Yuji is much stronger than Akaza so he’s likely not getting hurt much by him but at the same time he’s too slow to deal with Akaza so he likely gets worn down over time. If he lands a couple good hits he should win since Yuji can target souls with his attacks.

Deku gets Uraraka close then they send him to space. Muzan can’t be killed by them but he’s got no way of taking out Deku, Todoroki, Bakugo or Tokoyami.

I'm going with Class A on this many of them will definitely die but Muzan has no feats that imply he can contend with Deku, Bakugou, Shouto and Tokoyami (night time that is).

Current Deku took a blow from Shigaraki who is in the same realm of strength as All Might (most likely weakened) but even then he was taking and cancelling out City Block busting attacks (perhaps multi city block level as AFO was said to have taken out half of Kamino Ward with Air Cannon) so Deku's durability while weaker can handle those attacks.

There's also speed and we have Kirishima from an earlier arc reacting to a bullet and Rappa's punches which are said to be like a hail of bullets (more than once) or if you prefer he once pressured O'clock who has supersonic feats scaling from Number 6. At the very least current Deku is several times faster than Kirishima (assuming his percentages are linear increases).

Bakugou is at bare minimum equal to Muzan as he has building level feats of his own from several arcs earlier. Todoroki is comparable to him, has clashed with 100% Deku and is stated to have flames as hot as Endeavor's. Tokoyami is iffy but he's stated to be one of the strongest in Class A and with his Ragnarok forced Re Destro back.

Speed wise Bakugou is on a similar level to 30% who has more concrete speed scaling than Muzan. Todoroki and Tokoyami are harder to quantify but Todoroki is at least faster than 15% and Tokoyami is faster than 5% at least so they're still in the supersonic range as well.

As for Muzan's stats, his DC feats are building level based on his fight with the pillars. His speed is vague as he's vaguely (but much) faster than BoW Tanjirou who could dodge speed of sound attacks but we have no actual metric to judge him.

They also have a win condition through Uraraka who just needs to touch him once and the aforementioned heavy hitters can launch him into space.

I've heard lighting timing speed for demon slayer but the lighting they dodge is about as lighting as Kaminari's attacks from MHA. For example Kaigaku or Sekido who's attacks have no proof of being that fast.