Sasuke could be an ally. He also has his own issues with Konoha and would understand Naruto's need for revenge. They could combine their powers, with Naruto's massive chakra reserves and Sasuke's unique Sharingan abilities.
Another possible ally could be Gaara. Gaara and Naruto have a special bond. Gaara, as the Kazekage, has the power and resources of the Sand Village at his disposal. He might see Naruto's cause as just and offer his support, whether it be military or political, in Naruto's revenge against Konoha.
Kakashi might also side with Naruto. Despite his loyalty to Konoha, if he discovers the true extent of the wrongdoings against Naruto, he could choose to support Naruto. Kakashi has his own sense of justice and his relationship with Naruto could sway him to help.
Naruto could potentially be allied with those who oppose the traditional power structure of the ninja world, not just limited to specific villages. There might be a group of ninja who believe in a more equal and just ninja world without the dominance of the big five villages. He could also form an alliance with some mysterious and powerful individuals who have their own agendas and see Naruto as a useful tool outside of the Konoha context.
One possible plot could be that Naruto, after being wronged in some extreme way by Konoha, like false accusations of a heinous crime. He then uses his godlike powers, perhaps newfound abilities he acquired during some hidden training. He might start by targeting the people who directly wronged him, like certain elders or ninja who were part of the conspiracy against him. He could use his powers to expose their misdeeds to the rest of the village before deciding on more extreme forms of revenge.
One possible plot could be Naruto discovers a long - hidden conspiracy in Konoha that wronged his family, and he starts by using his influence outside the village to cut off Konoha's trade routes secretly. This slowly weakens Konoha's economy and forces the elders to come to him for negotiation.
Maybe the hidden organizations within Konoha that work in the shadows. They could have been involved in some plot against Naruto that led to his decision for revenge. They would be the ones trying to stop Naruto from exposing their secrets and exacting his revenge on the village as a whole.
One common theme is betrayal. Naruto might feel that Konoha has betrayed him in some way, like hiding important information or not standing up for him when he needed it. This sense of betrayal then drives his revenge.
In this fanfiction, Naruto might find allies among the shinobi who were also wrongly exiled from their own villages. They would share a common bond of being outcasts and would fight together against the system that exiled them. Additionally, there could be some rogue ninja with a sense of justice who believe in Naruto's cause and decide to stand by his side in the war.
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 possible 'naruto gets revenge on konoha fanfic' could be 'The Fall of Konoha by Naruto's Hand'. In this type of fanfic, Naruto might have reasons like feeling betrayed by the village's secrets or the way he was treated. However, these stories often deviate from the original spirit of the Naruto series which is more about forgiveness and unity.
Sasuke is often an ally. Since Sasuke also has his own issues with the village and a thirst for power, he may see Dark Naruto as a kindred spirit. They could team up to take on the Hidden Leaf together. Another common ally could be Orochimaru. Orochimaru is always interested in power and the unique abilities that Dark Naruto might possess. He could offer his knowledge and resources to help Dark Naruto in his revenge plot.
One possible reason could be jealousy. Naruto is very powerful and some in Konoha might be envious. For example, some minor clans might feel that Naruto, as an outsider in a sense, gets too much attention and resources. Another reason could be fear. His Nine - Tails power is so immense that some might fear he could lose control and endanger the village, so they betray him to try and eliminate the 'threat' before it's too late.