13/15 Zenitsu Agatsuma Defeated An Upper Moon On His Own He proved that he can be a capable fighter even while awake, defeating Upper Moon 6 on his own.
Fortunately, Zenitsu was able to single handedly beat the Upper Moon 6. Not only did he defeat the demon, he also created a seventh form called the Flaming Thunder God. These are the demons who have been given the title of Upper Moon 6 in Demon Slayer.
Demon Slayers are known for their strength and bravery in battle, but not Zenitsu. Despite his cowardice, he's one of the strongest in the series.
Inosuke always displayed raw strength and courage from the first few chapters of Demon Slayer. One might even argue that he was far stronger than Zenitsu during the first arc.
Overall, Zenitsu is an extraordinary powerful Demon Slayer capable of singlehandedly bringing down an Upper Rank, which said to be able to overpower 5 Hashira, in 10 minutes, albeit he would have beheaded Kaigaku in a heartbeat if it wasn't for his feelings of melancholy and pity.
Given how talented Tanjiro is, it's likely he'd defeat Zenitsu, even if the latter could fall asleep and call on his powers. Tanjiro's demonstrated his ability to take down more powerful demons and adapt to training on more than one occasion, so it just makes sense.
There are six forms, but Zenitsu could only learn the first form said to be the basis for the others yet he honed it to where he could fight against several strong demons. He later created a seventh form and defeated his former senior who had become the Upper Rank Six of the Twelve Kizuki.
9/10 Zenitsu Agatsuma Swiftly Defeated Kaigaku With A New Technique. Kaigaku was originally a disciple of Jigoro Kuwajima along with Zenitsu.
Yoriichi was born with the Demon Slayer mark and prowess in swordsmanship. His powers were beyond comparison as he defeated Muzan once and had him on the verge of death until he managed to escape.
He's mastered the first form to utter perfection making it deadly and he even made a godspeed version. I don't think he could take Kokushibo, but with enough training and a mark he would obliterate the other upper moons. Doma go bye bye.
Why Zenitsu could not become a Hashira in Demon Slayer. Fans have wondered whether Zenitsu ever got to realize his dream of becoming a Hashira at all. Unfortunately, the answer to this question would be, no, he did not. Zenitsu, along with Tanjiro and Inosuke got way stronger than average corps members with training.
Clearly, Tanjiro is much stronger than Zenitsu in Demon Slayer. Tanjiro beats Zenitsu in every relevant category to the question, whether fans directly see this or it's implied. The unique powers of Demon Slayer would normally make it difficult to power scale and compare two characters.
Zenitsu may be faint-hearted and tend to pass out when he gets too afraid - thus placing him into a bizarre kind of sleep - but he actually has stellar Nichirin Blade skills and breathing techniques. Fortunately for him, being unconscious is the key to activating his combat skills.
10) Zenitsu
He certainly has speed and was able to keep up with Daki during the Entertainment District arc. While some might say that he could one-shot the Upper Moon demon Kaigaku, the demon was nowhere near the level of an Upper Moon since he was not used to his powers.
Most Demon Slayers get crows, but the symbology of the sparrow makes Chuntarothe the perfect fit for Zenitsu. While all other Demon Slayers are gifted a crow after final selection, Zenitsu is assigned a sparrow instead.
Nezuko's Pyrokinesis aside, her viciously sharp claws slice through flesh like butter, and her powerful kicks can even obliterate an Upper-Moon, so she's far from harmless.
Even 400 years later, Muzan's fear of Yoriichi remained fully intact, as simply laying eyes on Tanjiro's hanafuda earrings caused him to recall their clash.
Mitsuri Kanroji is another Hashira who Tanjiro could definitely beat in Demon Slayer. Mitsuri's main trick up her sleeve is her muscle composition, which makes her muscles eight times denser than that of a normal human's. In other words, she's incredibly strong and powerful, and tough with plenty of endurance as well.
4/10 Satoru Gojo Beats Muzan Kibutsuji (Demon Slayer) By Drawing Out Their Battle Until The Sun Rises.
Nezuko Kamado
Zenitsu also protects Nezuko multiple times when she is in danger, evident during Zenitsu's first meeting with Inosuke Hashibira and the battle against Enmu in the train. Eventually Zenitsu and Nezuko would marry and start a family as evidenced by their descendants.
Zenitsu is a skilled and able member of the organization but gets easily scared when facing demons. But as the series continues, we watch him grow as he eventually overcomes his fear of demons and fights them head-on.
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.
Zenitsu creates his own form called Seventh Form: Honoikazuchi Nokami. Through this form, he is able to conjure a creature akin to a dragon that breathes thunder and fire. When combined with God Speed, his power and strength increase, giving him the ability to defeat demons like Kaiju, from the Upper Moon Six.
1/7 Seventh Form: Honoikazuchi No Kami
This mastery allowed Zenitsu to form a Seventh Form of Thunder Breathing that is unique only to him: Honoikazuchi no Kami. While this move might seem similar to Thunder Breathing's First Form, the speed and power of this technique are on a whole new level.
Thunder Breathing has 6 standard forms in total, with the first form said to be the foundation for all the other forms. However, Zenitsu Agatsuma developed a Seventh Form in order to stand on equal ground with Kaigaku, his former senior disciple under Jigoro who had become the Upper Rank Six of the Twelve Kizuki.