Well, it really depends on how the fanfic is written. If the fanfic focuses on Naruto's weaknesses and Danzo's preparedness, Danzo could potentially win. He has a lot of political power and experience. However, if it follows the general power scale of the Naruto universe, Naruto has a better chance. His positive energy and the power of friendship (a bit cheesy but true in Naruto's world) often help him overcome his opponents. Naruto also has the ability to quickly adapt to new situations, which would be a big plus against Danzo.
One possible plot twist could be that Danzo is actually being controlled by an even greater enemy. So, when Naruto is about to defeat him, he realizes that there's a bigger threat behind Danzo. Another could be that Danzo reveals a hidden power that he has been suppressing all along and suddenly becomes much stronger than Naruto expected.
In a straight - up fight, Itachi has some very powerful abilities. His genjutsu can be extremely difficult to break out of, and his ninjutsu attacks are strong. But Batman is no slouch. He has fought against some of the most powerful villains in the DC universe. He would study Itachi's moves and try to find a pattern. Batman might also use his wealth to create some sort of countermeasure to Itachi's Sharingan. Overall, it's a very close call and would likely depend on how the writer of the fanfiction wants the story to go.
One interesting scenario could be a battle in a dark, abandoned cityscape. Itachi's Sharingan abilities would give him an edge in terms of perception and illusions. Batman, on the other hand, would rely on his gadgets and combat skills. He might use smoke bombs to disrupt Itachi's line of sight and then try to get in close with his martial arts. Another scenario could be a mental battle. Itachi is used to psychological warfare, but Batman is also a master of getting into his opponents' heads. Itachi might try to use his genjutsu to break Batman's will, but Batman's strong mental discipline could resist it.
One interesting scenario could be a battle of wits. Itachi is known for his intelligence and Sakura has grown to be a very smart and capable ninja. They might engage in a mental duel where they try to outmaneuver each other with strategic moves and mind games.
In most traditional interpretations, Itachi would be favored to win due to his long - established reputation as a powerful and feared ninja. But in the realm of fanfiction, the writer can tip the scales in Sakura's favor. For example, if Sakura has mastered some sort of anti - Sharingan technique or has a power - up that nullifies Itachi's main abilities, she could emerge victorious.
I think young Sasuke would have a very intense reaction. He was so consumed by his hatred for Itachi at that young age. A Sasuke vs Itachi fanfiction would be like a trigger for him. He would be eager to see how the fictional fight is portrayed. If Sasuke in the fanfiction is shown as strong, it might fuel his own ego and make him strive even harder to become powerful. However, if the fanfiction shows Itachi as superior, it could enrage him. He might feel that it undermines his own goal of defeating Itachi and he might even want to find the writer to correct their 'wrong' view.
He'll likely lose his power and influence in the village. Once Naruto reveals his secrets, the villagers won't trust him anymore. His actions might be put on trial, and he could be exiled from the village.
One possible motive could be to gain control over Naruto's power. Since Naruto has the Nine - Tails within him, Danzo might want to use that power for his own political or military gains. He's always been power - hungry and sees Naruto as a tool to achieve his goals of making Konoha stronger in his own way, which might involve more underhanded and controlling methods.
It could also be a completely new character introduced into the fanfiction. A foreign ninja who was inspired by some of Danzo's ideas (not the bad ones) and comes to Konoha to take on the role of successor, bringing in new perspectives and ways of doing things.