Muzan Kibutsuji is the progenitor of demonkind in Demon Slayer and one of the most formidable characters in that world, with speed and strength few in the series can match. The comparison, however, argues that the Demon Slayer universe imposes limits on him, and that several demons from other anime possess abilities and feats that place them far beyond the Demon King.
Naruto's Kurama, the Nine-Tails, is presented as a particularly bad match. Its chakra reserves and raw physical power are on a scale Muzan cannot match. The comparison points to Pain's Chibaku Tensei barely registering against Kurama and to a half-chakra Tailed Beast Bomb matching the combined damage of five other Bijuu. Kurama's size also does not slow it down, and during the Fourth Shinobi Great War it took a Bijuu Bomb from the Ten-Tails and came away mostly unharmed. A Tailed Beast Bomb is described as a massive concentration of chakra far above the strongest Demon Slayer attack, meaning Muzan's regeneration would not be enough to survive it.
Black Clover's Lucifero is one of the strongest Devils belonging to the Qliphoth Tree, even though Lucius Zogratis later turns him into a pawn. His Gravity Magic can crush everything in its path and force powerful mages to the ground almost instantly. The comparison says that ability alone would be enough to crush Muzan, while Lucifero's overwhelming strength and capacity to warp space to close distance would counter any temporary speed advantage. Lucifero's presence also dominated fighters such as Asta, Yami, Yuno and Mereoleona, and Muzan lacks the Anti-Magic needed to weaken him.
Yu Yu Hakusho's Raizen is presented as far from his prime during a major showing. After Yusuke Urameshi is reborn through his Mazoku lineage, Raizen, who had not eaten for centuries, seizes control of Yusuke's body and easily defeats Shinobu Sensui, then the series' strongest character. He later overwhelms Yusuke in a duel. Muzan, by contrast, has spent hundreds of years eating and is at his prime during the Infinity Castle conflict. The comparison notes that Raizen at his peak surpassed later peers Yomi and Mukuro, and that Muzan would already be outmatched by either of them; facing Raizen is described as overkill.
Jujutsu Kaisen's Sukuna is described as having an arsenal built to dismantle enemies faster than they can recover, which directly threatens Muzan's regeneration. His Shrine-based attacks include Cleave, a devastating cutting technique, and Dismantle, which the comparison highlights as especially effective. Sukuna can also use Malevolent Shrine, an attack that exorcised Mahoraga for the first time, severely weakened Gojo enough for Sukuna to defeat him and nearly brought the world to ruin. Under certain conditions he can unleash Fuga, a flame arrow that instantly vaporized Jogo, Mahoraga and Choso. The Slash That Bisects the World is cited as another reason Muzan could not escape by running away; challenging Sukuna is framed as a death sentence.
The Misfit of Demon King Academy's Anos Voldigoad is the list's final and most extreme example. Unlike Muzan, whose title as Demon King does not translate into comparable power outside his setting, Anos can challenge the laws of his world and commands magic capable of circumventing the gods. His multiple resurrections further separate him from Muzan: one survives by reconstructing a mutilated body, while Anos always exists through his Source. The series' subtitle calls him History's Strongest Demon King Reincarnates and Goes to School with His Descendants. With Venuzdonoa, the Abolisher of Reason, Anos can break the universe and remake it, leaving Muzan as a helpless observer. The comparison concludes that Demon Slayer's mightiest villain would be little more than cannon fodder against him.
Sources: Comic Book Resources.