Pillars of the Demon Slayer are the elite members of the Demon Slayer Corps who are skilled in swordsmanship with prowess in Breathing Techniques. Becoming a Hashira is not an easy job but there are two ways through which the position of a Hashira is delegated to a Demon Slayer.
First, they have to prove their worth as a Kinoe-Ranked with a kill count of at least 50 demons and the second is being a Tsugoku of a Hashira, whereupon their death or retirement, a successor will be eligible to take the position along with the responsibilities.
Where Hashira’s haven’t been officially ranked by Ufotable, they can be categorized in terms of their Breathing Style and strength. The death of Flame Hashira: Kyojuro Rengoku broke so many viewer's hearts. He was arguably the strongest and was able to decapitate Upper-Rank Three: Akaza. Unfortunately, the mischievous demon escaped.
In the recent arc where the spotlight is on Tengen Uzui, it is still unclear how strong he is. Moreover, if he had to go against the Flame Hashira: Kyojuro Rengoku which is against the rules of the Demon Slayer Association. But leaving the rules aside, would Tengen be able to conquer victory over Kyojuro?
Is Tengen Uzui stronger than Kyojuro Rengoku in Demon Slayer?
Tengen Uzui’s Sound Breathing is certainly stronger but in front of Flame Breathing it is not. When Kyojuro Rengoku fought Upper-Rank Three Demon: Akaza, he was able to dominate and inflict fear upon him with his will of fire.
Akaza, a third powerful member of the Upper Demon Moons, had an upper hand with his quick regeneration abilities and Blood Demon Art. Kyojuro being a human can't regenerate his wounds but he fought till the end to fulfill his duty.
Furthermore, it was seen that Tengen was having a hard time keeping up with the Upper-Rank Six, Gyutaro, who was able to land a strike on him. Kyojuro Rengoku surpasses Tengen on many levels, be it strength, Breathing Technique, or battle Intellect. So to cut a long story short, Kyojuro Rengoku is more powerful than Tengen Uzui.
Among the Demon Slayer Corps, Kyojuro was acclaimed as a skilled combatant who was always dedicated to fulfilling his duty as a Hashira. Tengen admires and respects Kyojuro for his dedication to protecting human lives.
However, in the post-credit scene of Episode 15 of Demon Slayer Season 2, Tengen was seen talking to himself about being no match to Kyojuro. Out of the blue, Kyojuro appeared in spirit form to solace Tengen that he thinks too little of himself. Kyojuro tells Tengen that he has the strength and power to protect everyone and has to look over Tanjiro, Inosuke, and Zenitsu.