Anime often uses extreme situations and people in order to heighten the action and provide a spectacle to the viewer. Like superheroes, anime characters are often given strange and unusual powers in order to combat the monstrous enemies that they have to fight.
Sometimes, however, characters have no additional powers and are simply human. In the real world, this may not be an issue, but in some of the anime universes, they are at such odds that they could be considered incredibly weak. In these situations, a character can still fight and win, but they'll need to rely on their wits to do so.
10 Re: Zero: Natsuki Subaru
Natsuki Subaru is unlike standard isekai protagonists as he is transported to a fantasy world, however, his physical powers are unchanged from those in his former world. While he has the ability to return by death, this is not an overpowered magic skill that allows him to vanquish his foes through violence.
Even the ability itself, the ability to turn back time upon death does not mean he will win the next time. Instead, Subaru must think and understand what he knows of the future in order to figure out what the appropriate action is. He is only capable of victory if he uses his mind and plans ahead.
9 Deathnote: L Lawliet
When up against Light Yagami and his death god Ryuk, L has to use his wits to stay ahead of the calculating young man. When dealing with someone who can kill from a name, L must always be on alert and think ahead in order to not only survive but bring Light to justice.
While L does not succeed in his final goal, he still manages to make significant progress in hunting down the murderer, despite the strange methods and planning of the killings. L is willing to consider all possibilities and let the evidence take him where it will. While outsmarted in the end, he used his intelligence to great effect.
8 Dr Stone: Senku Ishigami
Living in the world of stone in the far-flung future, technology is essentially non-existent. As such, how is a super genius supposed to defeat a young man who is strong enough to beat up wild lions and other beasts? By using his brains and his encyclopedic knowledge of human technology!
With the assistance of some hard-working friends, Senku manages to create medicine, electricity, and even a tank. By using his intelligence Senku can outwit most of the dangers of the stone world and restart the progress of the human race.
7 Kakegerui: Yumeko Jabami
Not every anime revolves around invading monsters, aliens, and magical demon kings. Kakegerui is a series about gamblers pitting wits against others in an attempt to win, and Yumeko Jabami is someone who loves to gamble.
Her passion is enough to intimidate many players, even in the face of her own defeat, and even snatches victory from the jaws of defeat. Only her own understanding of how the games work and her boldness are enough to get her through the challenges, and she's smart enough to win regularly.
6 Mirai Nikki: Aru Akise
Mirai Nikki, also known as Future Diary gives characters the ability to predict the future. With this information, they can take action to counter the events foretold in their own diaries in the hope of surviving to the end of the game.
Akise is special in many ways, however, his great intellect is the real cause of the resolution to the events in the series. His own diary is powerful in its own right, but having the knowledge of what will happen is different from being able to use it, and only by understanding and using this information does he bring about his desired future.
5 No Game No Life: Sora & Shiro
In an alternate universe where everything is decided by playing games, Imanity is the weakest of the races. Sora and Shiro are humans and essentially Imanity from a different world and their skills fit perfectly together, always playing as the single player known as Blank.
The different species in the world have their talents with gods and flugel (angels) being able to use powerful magic. As the least powerful of the races, Sora and Shiro would appear to be most likely to lose, however by using their wits and skills, they are able to win a kingdom, expand it and even challenge the gods themselves.
4 Attack On Titan: Levi Ackerman
When facing giant monsters that could crush a person without breaking a sweat, Levi needs to be able to defend himself and the futuristic omnidirectional gear certainly helps that. However, the enemies in Attack On Titanare not simple mindless giants.
While much can be made of Levi's reactions, skills, and training, his real weapon is his mind. His quick thinking under pressure helps him to evade the trap set by Kenny Ackerman and outwit the anti-personnel squad, as well as look after his team in the field on scouting missions.
3 Mob Psycho 100: Reigan Arataka
Reigan Arataka is the greatest psychic of the 21st century, at least according to him. Despite having no psychic powers himself, he has made a living in being a psychic consultant and seems to have performed fairly well before he encounters Mob, a genuine psychic.
While the uncharitable majority would likely call him a huckster, his speaking skills and ability to rapidly understand people allow him to manipulate others easily and stay in business. While there are moral issues surrounding his business practices, there is no doubt that this man lives through his wits and makes a good deal of money doing so.
2 Cowboy Bebop: Spike Spiegel
Lazy, careless, and easily distracted are all ways of describing Spike Spiegel, however, he can also be described as skilled, strong, and intelligent. While Spike attempts to earn a living as a bounty hunter, he constantly faces danger and needs to use his wits to stay one step ahead of his bounty.
Unfortunately, Spike also needs to use his wits to get out of difficult situations involving a runaway superdog, starvation, a monster made from leftovers, and a brainwashing cult. Though the action often takes center stage in the series, Spike's intelligence should not be underestimated.
1 Fullmetal Alchemist Brotherhood: Ling Yao
The characters of Fullmetal Alchemist Brotherhood are all highly detailed and complex with their own motivations. While Ling Yao may want the philosopher's stone to secure the rule of an empire, he is unable to simply take it. Yao has capable guards and is skilled in fighting himself, but that is not what gets him closer to his goal.
Yao is quick thinking, able to plan out his fighting strategy on the fly, and fights well against homunculi without any alchemy skills himself. He will take whatever action is needed to secure his fortune, even if it comes to making a deal with the enemy and by doing so, his success is assured.