Naruto is often one of the main characters. He is the central figure in the Naruto universe, so it's likely he'll play a major role in any fanfiction related to it. The striper character is also a main character, as the story revolves around this unique element.
Sakura, who has a long - standing relationship with Naruto in the original story, would probably be a key female character. Hinata, too, as she has deep feelings for Naruto. There might also be other female ninjas like Ino or Temari who could be part of the story to show Naruto's charm towards different types of women.
Obviously Naruto would be one of the main characters. Depending on the plot, Sasuke could also be involved, either as a helper or an obstacle. Sakura might also play a role, perhaps as a healer trying to save Naruto. There could also be new characters created specifically for this fanfiction, like a dark figure who is responsible for Naruto's 'dead man walking' situation.
Well, obviously Naruto and Logan are the main characters. Naruto brings his ninja skills and positive attitude, while Logan has his mutant abilities and a lot of life experience.
Naruto himself is obviously very popular as it's his fanfiction. But Sasuke also often plays a big role. Fans love to explore their relationship further in fan - made stories.
There might be stories where Naruto forms different relationships. For example, he could have a closer bond with characters that were more on the periphery in the original, like some of the minor ninja from other villages. This could lead to all kinds of new adventures and storylines.
Sakura is often a main female character in such fanfictions. She might be portrayed as having a different relationship with Naruto, who is the ladies man in this case. Maybe she's initially jealous of all the female attention he gets but then realizes her true feelings for him.
Madara Uchiha could also be the main antagonist. Even if he was defeated before, in this fanfiction, he could come back with a new plan related to the Ten - Tails. He might want to use Naruto as a vessel to fully revive himself and then take over the Ten - Tails' power.
The Akatsuki could still be major villains, but with a twist. They could be interested in Naruto's connection to Iron Man and his technology. Maybe they want to use it to enhance their own powers or to create a new type of bijuu using Stark's technology. Another option could be a new villain from the Iron Man universe, like Justin Hammer, who finds his way into the Naruto world and decides to use the chaos there to his advantage by creating his own criminal empire using ninja and technology combined.
Well, the Kingpin could be a main villain. He could see Naruto as a threat to his criminal empire in New York. He might hire some ninja mercenaries from the Naruto universe to take him down. And then there's Electro, who could be enhanced by some sort of chakra - based technology. He could use his new powers to cause chaos in the city and target Naruto specifically, thinking that he's the key to getting even more power.