Momo Yaoyorozu is a fan favorite in My Hero Academia, often praised for her capabilities by other characters and fans alike. She is an intelligent and dedicated hero-in-training achieving her spot in U.A. High School's hero course through recommendations while also serving as Class 1-A's Vice President. However, after taking a closer look at the requirements and limitations of her Quirk, it's hard to ignore the fact her powers are unsuited for the rigorous demands of hero work.
Momo's Quirk, Creation, allows her to create inanimate objects by transforming the molecular level of her fat cells and releasing whatever she creates through exposed skin. Her Quirk is fueled by food, so the more she eats, the more she can produce. However, there's only so much fuel her body can hold, meaning that there's only so much she can create before reaching her limits as exhaustion takes over. The more complicated and larger an object is, the more time is needed to create it. This is not practical in an emergency situation on the battlefield, where every second could mean life or death.
To utilize her Quirk to its full potential, Momo needs to understand the molecular structure of whatever object she wants to create. In addition to a proper diet, Momo needs a deep understanding of the materials required to build an object from scratch in order to reproduce it. This likely contributes to her studious nature, since her intellect becomes key in exhibiting such a complicated Quirk on a level needed to keep up with the standards set by U.A.. In order for Creation to be especially useful, much studying is required. Not only does Momo have to learn how to build many things from the molecular structure, but she needs to know how to make use of whatever she creates. Luckily Creation suits her personality, but if someone with a less focused nature, like Kaminari, were born with such a Quirk, it would not be used in the same efficient way.
While Creation can definitely be a useful Quirk, it requires too much study time and cannot be used well in combat. In the Sports Festival, Momo was pitted against Fumikage Tokoyami and created a sword and shield to combat Dark Shadow. In a one-on-one battle with no chance of taking advantage of outside factors, like a unique terrain, Momo was left to her own devices and lost. In this situation, she could not counter against an offensive attack, which diminished her self-esteem. Momo knew how to create a sword for offense and a shield for defense, which theoretically makes sense, but did not know how to properly wield either. If she was placed in a hand-to-hand combat situation, she would likely lose because her Quirk is not an offensive one made for quick, incoming attacks.
It is worth noting that Momo has utilized her Quirk in battles effectively. When she and Shoto were partnered against Aizawa for their practical exam, it was Momo who came up with and executed such a complicated plan to win along with Shoto's help. In many instances, we see her create canons and other weapons that can be used in battle. However, this also further proves that she might be more suited for a support position. Hero work requires fighting on the frontlines, which isn't the best course of action to fully utilize Creation. In My Hero Academia: Heroes Rising, she is one of the few people who can maximize their resources and in battle, acts as a first line of defense. While Momo has a strong intellectual ability, she may be better equipped to lead from the shadows, providing weapons, aid and insight as needed.
While Momo makes the most of her Quirk and her potential, Creation is not suited for the frontlines required of a Pro Hero. Unless she becomes a master in wielding weaponry, Momo is at a disadvantage in close combat. The best way to use her intellect and Quirk to its fullest extent is to place her in a tactical position on a mission to achieve more calculated and precise attacks. In terms of fighting ability, she is better equipped at long range attacks like her canons, or through support combat, which has proven useful on many occasions.