Asta and Yuno are the two main characters of Black Clover. Asta is the possessor of the rare five-leaf clover grimoire whereas Yuno is the rightful heir to the throne of the Spade kingdom. Throughout the series, they both prove their prowess against several strong enemies. The friendly rivalry between Asta and Yuno is not unknown among fans. Despite being polar opposites of one another, the two are close friends. They grew up in the same orphanage and respect each as rivals. Asta always yearned for magic power, which he never got. However, his life began to change when he received his grimoire.
Yuno likewise received a rare four-leaf clover grimoire, which was said to be a sign of good luck. Yuno was recruited by the best Magic Knight Squad in the kingdom, while Asta was chosen by the worst squad. However, that didn't stop him from striving to be the Wizard King. As Asta and Yuno worked toward achieving their goal, they came across several enemies along the way, becoming stronger by the day. Looking back to the time when they had just started their journey from the Forsaken Realm to the Royal Capital, it is clear how much they grew. As things turned out, they were always on par with one another. However, if they were to fight each other head-on, who would win?
Asta Has Superior Physical Strength
Asta would definitely have the upper hand against Yuno in terms of physical strength. Since Asta didn't have any magic, he did whatever he could to become stronger, training relentlessly to build up his physical strength. In the end, his efforts were not in vain, as he is able to do over a thousand push-ups without a break. The swords he received in his grimoire are extremely heavy, yet he can wield them without any problem. Moreover, the Queen of the Witches enhanced Asta's arm strength using Blood Magic when he was hexed by Vetto.
On the other hand, Yuno was blessed with extremely powerful wind magic. Ever since he was a child, he relied on his magic rather than brute strength for every little thing. Even when he became a Magic Knight, he never had to use physical attacks because of his overwhelming magic.
Yuno Has Mana, but Asta Has His Grimoire
Asta doesn't possess any mana, but his grimoire allows him to nullify all kinds of magic, regardless of how strong it is. Moreover, unlike those with magic who drain their mana during battle, Asta doesn't have that weakness. He can go on fighting as long as it doesn't drain him physically. In addition, although he cannot sense mana, he can sense ki. In that sense, he has the upper hand against his enemies because although they won't be able to sense Asta because of his lack of magic, Asta can sense them from a distance. This makes it easy for him to form sneak attacks against extremely powerful enemies.
On the other hand, Yuno has a massive reserve of mana as a member of the royal family. He has a wind attribute, meaning his attacks are very flexible and versatile. Wind mages are known for their keen senses, including hearing, eyesight, and mana detection. Unlike Asta, who is a close-range fighter, Yuno can fight the enemy head-on as well as from a distance. He can cast two powerful spells at the same time -- something even strong mages have difficulty with. Moreover, he has the wind spirit by his side to help him out in battle. Yuno is especially skilled in Mana Zone and wielding spirit magic.
Both Asta and Yuno Host Otherworldly Entities
Asta is the host of a low-ranking devil named Liebe, who possesses Anti-Magic. Liebe was a devil from the first level of the underworld who resides in Licht's grimoire and chose Asta as his next wielder. Just like Asta, Liebe possesses no mana and is unable to use magic. Therefore, he can use Anti-Magic without suffering the weakening effects since he has no mana to drain. The fact that Asta is able to use Anti-Magic is only because Liebe chose him. Asta's Devil Union allows him to further enhance his anti-magic abilities. The power is so great that he can nullify a Gravity Singularity and coat weapons with Anti-Magic.
Conversely, Yuno was chosen by the wind spirit Sylph. The fact that a spirit chose him has something to do with both strength and luck. Sylph once mentioned that he was chosen only because of his unparalleled magic and talent. Sylph always stays by Yuno's side, and the latter can ask her to assist him in battle anytime. Just like Asta and Liebe who use the same element, Yuno and Sylph also share the same attribute. Therefore, once Yuno gains Slyph's powers for his own, he can dominate his enemies with ease.
Asta vs. Yuno: Who Would Win in a Fight?
Asta and Yuno are each strong in their own right, so if they were to engage in a serious one-on-one battle, both sides would take serious damage. Ever since they joined the Magic Knights Squad, they have shown great improvement and fought several difficult battles. Especially in the Spade Kingdom, they have fought enemies that even the Squad Captains have difficulty against. In a battle, Asta can nullify Yuno's wind magic to a certain level, but he cannot evade all attacks since Yuno excels at speed. Moreover, Asta's incredible physical strength would prove a challenge to Yuno.
Even if Yuno used powerful techniques such as Mana Zone and Spirit of Boreass, Asta could render these useless by uniting with Liebe, who is far more substantial than Sylph. In terms of stages, Yuno is a Stage 0 mage -- the highest rank any mage can get; however, normal magic doesn't do well against devils. Asta is an Arcane mage, and the host of a devil. Therefore, despite being one of the strongest mages in the series, Yuno will most likely lose against Asta. Regardless, even if Asta were to win, it wouldn't be without consequences, as Asta would have a difficult time defeating Yuno.