Who could be some unexpected participants in a One Punch Man tournament fanfiction?

Well, perhaps a character from a very low - key anime that no one expects. Like a character from a slice - of - life anime who has some hidden power. Maybe a schoolgirl who can control time in short bursts, but has been keeping it a secret in her normal life.

One possible plot could be that a new and extremely powerful villain emerges who is not impressed by Saitama's one - punch ability at first. This villain manipulates the rules of the tournament to his advantage, creating unfair match - ups for the heroes. The heroes then have to find a way to overcome these obstacles while also dealing with their own rivalries and personal growth. For example, Genos could be paired against a much stronger opponent early on, and in the process of trying to defeat this foe, he discovers a new power - up within himself.

Filch could be an unexpected character. He might enter the tournament in a comical way, like he accidentally stumbles into the selection process and ends up being a participant. Another could be Peeves. He could disrupt the tournament in his usual mischievous way, or perhaps he is made a part of a task where the competitors have to outwit him.

Genos could be an unexpected opponent. He might be forced to fight Saitama due to some mind - control or a misunderstanding in the rules of the tournament. It would be really interesting to see how Saitama would handle fighting his own disciple, and how Genos would fare against his master's incredible strength.

Iruka. He's mostly seen as a teacher and not a combat - heavy character. But in fanfiction, he could be given some hidden powers or a special training arc before the tournament. His inclusion would be unexpected because everyone underestimates him, but he could use his knowledge of Naruto and the other ninja to come up with unique strategies in the tournament.

Captain Jack Sparrow from the Pirates of the Caribbean world. Imagine him being thrown into the Tournament of Power. His wily and unpredictable nature, along with his knack for getting out of tough situations, would make for some really interesting interactions with the more serious combatants in the tournament. He could use his cunning to outwit opponents rather than relying on pure strength.

The concept could be expanded by giving the punch different properties. For instance, it could have the ability to nullify an enemy's special powers instead of just knocking them out physically.

Genos would be an obvious choice as his student. Genos is always eager to learn from Saitama and improve his skills. Also, some of the lower - ranked heroes like Mumen Rider could be his students. Mumen Rider has a strong sense of justice but lacks in power, and Saitama could teach him some basic self - defense techniques.

Another possibility is that the main antagonist is a corrupted hero. This hero, who has turned to the dark side, sees Kombu Infinity as a threat to his new - found power and plans. He uses his knowledge of the hero association and his own powers to try and eliminate Kombu Infinity, all while trying to keep his true identity a secret from the other heroes.

Maybe a former villain who is reborn with a new moral compass. They could start using their villainous skills for good, which would make for an interesting main character as they navigate their new life in the world of One Punch Man, trying to make amends for their past deeds while also fighting new threats.