Well, Gojo could be a super powerful outsider. Maybe he comes to the Naruto world to study its unique chakra system. His Infinity ability would be a game - changer. He could use it to easily deflect most ninjutsu attacks. And his Six Eyes could help him detect hidden enemies or traps that normal shinobi might miss.
In 'naruto power mimic fanfiction', one interesting concept could be how characters adapt Naruto's unique jutsus. For example, a character might try to mimic the Rasengan. They would need to understand the chakra control required, which is a key aspect of Naruto's power. Another concept could be the social implications. If someone mimics Naruto's powers in a fanfic, how do the other characters in that fictional world react? Do they see it as a threat or an inspiration?
Naruto himself is often a central character in these fanfictions, as the source of the powers being mimicked. Sasuke is also quite popular. He has his own set of powerful abilities, and in fanfictions, he might be involved in situations where others try to mimic Naruto's powers in relation to him, either as a rival or an ally. Sakura could also be involved. She might be the one observing or helping someone mimic Naruto's powers, especially considering her growth as a medical ninja and her own combat abilities.
He could play the role of a disruptor. Just like his character in his own universe, he would disrupt the existing power dynamics in Naruto. His overpowered abilities would make him a force to be reckoned with, whether he's on the side of good or bad.
I don't have a definite answer for you. The Mimic might be based on a combination of folklore, myths, or the author's imagination. It's hard to pin down a specific source.