Tanjirō's resemblance to Yoriichi (like from Muzan's perspective), would trigger his memories and cause him to accept death. AND since its against Kokushibō and not Muzan, there's not poison that'll mess him up. So I would say Tanjiro would win.
2) Tanjiro Kamado
With his awakened Demon Slayer Mark along with his Transparent World, he could match up with Kokushibo's speed. Moreover, Tanjiro's Sun Breathing is too lethal for Kokushibo and with his swordsmanship he can rival the latter.
Thirteenth Form
This move was devised by Tanjiro solely to defeat Muzan. After all, the twelve hearts that Muzan could move around his body needed to be downed in one fell swoop, which is why Tanjiro resorted to this powerful technique.
Tanjiro, in his demon form, had all of Muzan's blood, making him far more potent than Kokushibo. While the sun is every demon's kryptonite, Tanjiro had conquered the sun in his demon form. Not only that, but he could use the Breath of the Sun after having his physical abilities enhanced drastically.
Tanjiro sets out on a dangerous journey to find a way to return his sister to normal and destroy the demon who ruined his life. The fight with Kokushibo, the highest-ranking demon among Muzan's servants, is over.
However, against all odds, Tanjiro along with the rest of his crew were able to defeat the Upper Moon 6. This was also the first time he activated his Demon Slayer Mark as well. Fans absolutely loved this fight in the Entertainment District arc.
Kokushibo was loyal to Muzan, acting as enforcer to the Twelve Kizuki. In return, Muzan sees him as a business partner, possibly due to his fanatic loyalty to him, being his strongest Demon and because the two were jointly responsible for almost exterminating Sun Breathing.
Thanks to Muzan, the demon form of Tanjiro has the fastest regeneration and the strength to avert all physical attacks. Moreover, just like his sister Nezuko, Tanjiro acquires resistance against the sun, making him completely invincible against any human.
In his own franchise, Tanjiro is outclassed by most of the nine Hashira as of the end of season 1, including Giyu Tomioka. It's easy to compare Tanjiro's strength to Giyu's — since they are both demon slayers — and they even use the same element: water.
No, Even in end of manga, there is no indication that Tanjiro ever surpass Yorichii in power.
Tanjiro isn't Faster Than Zenitsu, not at all. He is Strong but Slow. So, Zenitsu Will Probably Chop Him Down to bits before tanjiro even pulls out his sword properly. There ya go!
Those who have read the manga know that Tanjiro's powers grow exponentially towards the end of the series. His skill and overall combat abilities could be compared to that of a Hashira's. That being said, there is absolutely no chance for Tanjiro Kamado to be able to beat Kibutsuji Muzan.
"Breath of the Sun: Thirteenth Style") is the thirteenth form the Sun Breathing and the pinnacle of all Breathing techniques in history. This technique was created by Yoriichi Tsugikuni himself in order defeat Muzan Kibutsuji.
4) Kokushibo
The Upper Moon 1 is a swordsman and is capable of causing a ton of destruction from any range. Nezuko will have to give her all to just keep up with someone like him. Kokushibo would easily be able to defeat her in a 1v1 combat.
Rimuru Tempest becomes a God towards the end of the series and can travel back in time and travel between worlds. His space-time abilities alone would be enough to beat Yoriichi. This character is often stated to be stronger than Goku, despite the community being quite divided on this topic.
10 Can Beat: Tanjiro
The fact that Giyu easily takes down Rui, a demon that nearly kills both Tanjiro and Nezuko, also proves that he's a more powerful demon slayer than Tanjiro — at least currently. He sees the potential in the recruit, so it's possible Tanjiro could one day outdo him in battle.
Demon Slayer's season 3's latest episode has left fans on edge with Tanjiro's discovery of Yoriichi Tsugikuni's Type Zero sword.
1 Tanjiro's Patience Paves The Way To A Close Friendship With Inosuke Hashibira.
After awakening his demon slayer mark, Giyu greatly overpowers Akaza. However, he is able to keep up with the fight only because of Tanjiro. If Giyu had soloed against Akaza, he would have died.
The warrior Muzan feared was a swordsman named Yoriichi Tsugikuni. Yoriichi was the only slayer before Tanjiro who came close to killing Muzan, and the flashback of their fight occurred in Chapter 187.
Muzan himself never thought highly of Daki and didn't reciprocate her devotion whatsoever, only ever talking to her to sweetly manipulate her into defeating Demon Slayers on his behalf.
The only Demon he despises the most is the Upper Rank Two: Doma. It is quite a shocker that the second most potent Demon in the Demon Slayer is not Muzan's favorite.