Sasuke could be one of the characters to support Naruto. Given their complex relationship and Sasuke's own issues with Konoha in the past, he might see Naruto's cause as just. Another one could be Jiraiya. If he were alive and found out about the real reasons behind Naruto's revenge, he might side with Naruto as he always cared for him deeply. Also, some of the outcast ninja within Konoha, like those who have been discriminated against because of their bloodline or lack of skills, might support Naruto as they also have grudges against the village system.
One character who might support Naruto is Orochimaru. Despite being an antagonist in the original story, in a 'Naruto revenge on Konoha fanfiction', he could see Naruto's revenge as an opportunity to gain power or knowledge. He might offer his assistance in terms of his vast knowledge of forbidden jutsu and his network of spies. Also, some of the foreign ninja who have had bad experiences with Konoha in the past might join Naruto. For example, ninja from a village that was once attacked by Konoha unjustly could see Naruto's revenge as a way to get back at Konoha.
Kakashi could potentially support Naruto. Although he is loyal to Konoha, if he discovers that Konoha has truly wronged Naruto in an unforgivable way, his sense of justice might lead him to support Naruto. Then there are the tailed beasts. Since Naruto has a connection with them, they might see his revenge as a way to break free from Konoha's control over them as well. And some of the older ninja who have seen the darker side of Konoha's politics, like Tsunade, might also back Naruto if she realizes that Konoha has crossed a line with Naruto.
Sasuke could be one of the characters to support Naruto. They have a deep bond, and Sasuke might understand Naruto's reasons for wanting to change Konoha. Also, Shikamaru, being a smart strategist, might see the potential in Naruto's plan and choose to support him.
Obviously, Naruto would be the main character as it's about his revenge on Konoha. Sasuke could also play a significant role. He has his own issues with the village, and he might either support Naruto's revenge or try to stop him depending on how his character is developed in the fanfic. Sakura might be there too. She could be caught in the middle, trying to figure out whether to side with Naruto or stay loyal to Konoha. And Kakashi, as Naruto's former teacher, would likely be involved. He might be one of the people Naruto has to face if he's set on his revenge, or he could be trying to reason with Naruto.
Definitely Sasuke. Their bond is such that Sasuke would not stand by and let Naruto destroy Konoha. He has his own reasons to protect the village now. Shikamaru is also a likely candidate. He's intelligent and would quickly figure out that Naruto's actions are wrong. He would use his strategic mind to try and stop Naruto. And Hinata, who loves Naruto deeply, would oppose him in the hopes of bringing him back to his senses.
Sakura might support Naruto. Despite the exile, she could believe in his innocence and try to find ways to help him. Also, Kakashi, who has always had a connection with Naruto, would be likely to support him. He might secretly provide Naruto with some resources or training advice.
Iruka sensei is almost certain to be in it. He has always been important in Naruto's life. Also, Sakura might be there. She could be one of the first to welcome Naruto or perhaps she might initially be a bit cold because of her past feelings for Sasuke. Other characters like Kakashi sensei could also make an appearance, guiding Naruto in his new life in Konoha.
Iruka could be one. He has always believed in Naruto from the start. Also, Jiraiya might be another. He was Naruto's teacher and had a deep understanding of Naruto's potential. And Kakashi could also support him. He has seen Naruto grow and might recognize his sage powers even when others don't.
Sasuke is often one of the characters. Given their complex relationship, Sasuke might see Naruto's banishment as another wrong done by the village and decide to support him in his revenge, especially if it means taking on the village's corrupt elements.
Sasuke would likely be involved. He has his own issues with Konoha and might side with Naruto, either out of friendship or his own vendetta against the village. Also, the elders of Konoha like Danzo could be important characters as they might be the ones behind Naruto's banishment.
In this fanfiction, Naruto is the key figure. However, characters like Shikamaru, who is known for his intelligence, might also be involved. He could be helping to plan Naruto's welcome or dealing with any potential issues that Naruto's return might bring. Also, Hinata, given her relationship with Naruto, would surely be part of the story. And the elders of the village may also play a role, as they often have a say in important matters regarding the village and its shinobi.
Obviously, Naruto himself would be a main character. His friends like Sasuke and Sakura are also likely to be important. Maybe their children could also play significant roles as they grow up in the post - return to Konoha era.