Ouyang Feng was the weakest of the Five Uniques in Legend of the Condor Heroes. Although the weakest of the Five Uniques was not absolute and was only relative, according to the descriptions in document 1 and document 3, Ouyang Feng had suffered heavy injuries in his battle with Hong Qigong and Wang Chongyang. He had even suffered mental damage. Hence, Ouyang Feng could be considered the weakest of the Five Uniques.
In my opinion, it could be Mr. Bumble from 'Oliver Twist'. He is a rather pathetic and weak character. He is self - serving, cowardly, and easily manipulated. He is constantly outwitted by those around him, especially by the wily characters in the underbelly of London society that Dickens portrays.
In my opinion, the weakest fictional character could vary. It could be someone who constantly fails, has no determination, or is easily overcome by challenges. However, what makes a character weak is subjective and can change depending on the viewer's perspective.
Sasuke could also be a possibility for the 6th Hokage in the fanfic. He has grown stronger over the years and his unique perspective on the ninja world could bring new ideas to the leadership of the Hidden Leaf. He might start off as a controversial choice but prove himself through his actions in protecting the village and making tough decisions.
Sasuke could be an alternative. He has strong ninja skills and a deep understanding of the ninja world. His experiences have made him grow into a very capable person, and his Sharingan gives him an edge in combat and strategic planning.
Even Naruto himself could be a subject of this 'evil Hokage' concept in fanfiction. Maybe he is possessed by some dark entity or has a major change of heart due to some extreme event. This would completely change his character and turn him into an evil Hokage, which would be a very interesting and unexpected twist.
Shikamaru is another possibility. He is known for his strategic mind. As Hokage, he could use his intelligence to make wise decisions for the village. He may not have the brute strength of Naruto or Sasuke, but his ability to plan and analyze situations would be invaluable in leading Konoha.
His friends like Sakura and Shikamaru would surely support him. Sakura, with her medical skills, could be an important part of his regime, providing healthcare for the ninjas. Shikamaru, being intelligent, could offer strategic advice. Also, the younger generation of ninjas who have been inspired by Naruto would be his strong supporters, as they believe in his leadership and the new direction he could take the village in.
Sasuke could also be a candidate in some fanfics. He has his own set of powerful abilities and a complex personality. A story could be written where he decides to take on the role of Hokage at a young age to bring about change in the village in his own way, perhaps using his Sharingan and new techniques he develops.