If Shinobu goes 1v1 against Akaza, she can turn the tides in her favor by restricting his regenerative abilities with her poison or could even kill him with her fast-paced combat skills.
Gyomei Himejima is the strongest Hashira in Demon Slayer. Even the Hashiras who are filled with pride, acknowledged his skill and strength. As a child he was able to save a child from a demon by physically beating it for hours. He, along with Sanemi Shinazugawa were able to beat the Upper Moon 1, Kokushibo.
Rengoku and another hashira can definitely hold Akaza off until dawn without anyone dying but that's it.
At the end of the day, none of the Hashira could've defeated Akaza – even though a few of them could've succeeded in decapitating him.
Muichiro can defeat Akaza easily with his petite body that leverages his speed. Moreover, his ability of Transparent World can aid him in landing a fatal blow on Akaza's weak spot.
It affects even the strongest of the Upper Rank demons. This would be effective against Akaza because the only people he refuses to eat are women, since that goes against his morals. Sanemi also has excellent control of his muscles, saving himself from fatal injuries by closing them up himself.
1) Yoriichi Tsugikuni
He was the creator of Sun Breathing which is the most powerful Breathing technique. Yoriichi was the only person who could defeat the progenitor of all the demons, Muzan Kibutsuji. Doma is an inferior opponent, as he won't even last a second in front of Yoriichi.
Gyomei is stronger and faster overall, but Akaza's weird cockroach like tenacity can drag the fight into an attrition battle in which case, it depends on how close to sunrise they fight.
Tanjiro decapitates Akaza with the Hinokami Kagura: Setting Sun Transformation. Akaza was bewildered, wondering how Tanjiro did not have any fighting spirit, comparing this feeling to fighting against a plant. He acknowledges that Tanjiro surpassed his speed.
However, when Keizo and Koyuki eventually got killed, Akaza went berserk and ended up killing more than 60 people just with his bare hands.
Akaza always held back too much, it's clear from his movements that he's not fully utilizing his martial prowess, meaning yoriichi should be able to win.
Sound Hashira
He is the fastest Hashira, and the second physically strongest. Obviously, then, Tengen Uzui is rather proud. He is demanding, fussy, boastful, and prone to selfishness. But he is also ultimately kind and caring, with great love for his three wives as well as the other Hashira.
The Water Hashira, Giyu, survived the "Infinity Castle" arc after fighting beside Tanjiro against Akaza and Muzan.
Despite being the lowest of the Upper Ranks, Gyutaro showed much of his demonic prowess by making Tengen lose his left arm and his left eye in battle. However, Giyu would have been a better opponent for the demon and could have defeated him without losing any limbs.
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.
2) Rengoku
However, Rengoku was forced to face off against Akaza who was Upper Moon 3. The Flame Hashira carried out his duties until his death as he did not let his comrades get injured.
1) Kyojuro Rengoku
Unfortunately, Rengoku was killed by Akaza, the Upper Moon 3. This took place when he, along with Tanjiro, Zenitsu, and Inosuke, boarded the Mugen train to investigate cases of missing people.
As the Flame Hashira, Kyojuro is his generation's most skilled Flame Breathing user. He became evidently proficient in fighting with this Breathing Style, being able to singlehandedly defeat former Lower Rank Two, Hairo and later hold his own against Upper Rank Three, Akaza.
Mitsuri. The love Hashira and upcoming featured character of season 3, Mitsuri is best known for her extreme affection for everyone in the Demon Slayer Corps.
As a result, Tengen Uzui has to deal with the moniker of being the least powerful Hashira around.
1) Gyomei. Gyomei Himejima is the strongest Hashira in Demon Slayer. This fact has been established in the manga as Tanjiro, Inosuke and Zenitsu all agree that he is the strongest member of the Demon Slayer Corps.
5) Yoriichi
Case in point: he was the only one who could single-handedly take on Muzan and drive him to a corner. Yoriichi would be able to defeat every single Hashira on this list without breaking a sweat. Such was his reputation and skill in swordsmanship.
And kokushibo is the second best swordsman. And michchikatsu is arguably the second strongest demon slayer. Kokushibo wins but is at his porcupine stage. With his porcupine stage he 16th forms and wrecks doma's budda and shreds akaza.
With that said, all Hashira in Demon Slayer have one glaring flaw: they're only human. As such, they're not infallible and are certainly not tougher than their demon enemies. This results in some rather lopsided matches and emotionally-charged oversights on their part.