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.
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.
A possible plot is that with Gojo's power, Naruto is able to see the world in a new way. He can now perceive curses in the ninja world that were previously hidden. This leads to a whole new side - quest where he has to deal with these curses while still maintaining his duties as a ninja. He might also use Gojo's power to teach other ninjas a new way of fighting, changing the ninja combat system.
Toge Inumaki is important too. His special cursed speech ability makes him stand out. Also, the principal of the school, Masamichi Yaga, is likely to be important as he is in a position of authority and has an influence on Gojo and the other students. There could be other characters like the members of different clans that also play roles in the complex web of the story.