Danzo could be a Ra's al Ghul type of villain. He has his own secretive motives and a thirst for power. He might see Naruto's new Batman - inspired ways as a threat to his control over Konoha. So, he would try to undermine Naruto at every turn, and Naruto would have to expose Danzo's true nature while also protecting the village from his schemes.
Orochimaru could be like the Joker. He's already a bit of a mad scientist and likes to play with people's lives. Just as the Joker likes to create chaos, Orochimaru could do the same in Konoha, and Naruto, as the Batman - inspired hero, would have to stop him. He could also have some henchmen like the Joker does.
Ra's al Ghul could also be a possible villain. He could use his influence on Robin, maybe through some sort of brainwashing or false promises. Ra's al Ghul might convince Robin that Batman's methods are holding him back from achieving true power or justice, and this could start the fight. Also, there's always the possibility of a new, original villain created specifically for the fanfiction. This villain could target their relationship and use mind - games to make Batman and Robin turn against each other.
The Akatsuki could still be the main villains. In a secret agent Naruto fanfic, they could be even more devious, using undercover agents of their own to disrupt the shinobi world while Naruto tries to stop their grand plan of collecting all the tailed beasts.
The demons from Inuyasha's world that resent the idea of a half - human, half - demon having such a powerful combination of abilities could be villains. They might see Naruto as a threat to their existence or way of life and try to eliminate him. Also, there could be ninja who are jealous of Naruto's newfound powers and team up with these demons to take him down.
The Joker could still be a major villain. Even with Batman as a god, the Joker might find some twisted way to challenge him. Maybe he'd try to drive Batman to use his god - like powers in a way that goes against his moral code. Ra's al Ghul could also be a villain. He might see Batman's new godhood as a perversion of the natural order and seek to destroy him.
The Joker is probably the most popular. His chaotic and unpredictable nature creates a great contrast with Batman's brooding and methodical approach. Harley Quinn is also a common choice, especially in stories that explore her complex relationship with both the Joker and Batman. Then there's Bane, who is known for his physical and mental strength, and his battles with Batman are always intense in fanfiction.
The Joker is probably one of the most popular. His chaotic and unpredictable nature makes him a great character to explore in fanfiction. Writers can come up with all kinds of crazy scenarios for him. Harley Quinn is also very popular. Her relationship with the Joker and her own journey of self - discovery are often the focus of fanfictions. Another popular one is Bane. His physical strength and strategic mind are interesting to write about, especially in battles against Batman. And then there's Catwoman, who has that alluring and complex personality that draws in readers and writers alike.
The Joker is a very well - known main villain. He's completely unpredictable and his chaotic nature provides a great contrast to Batman's order - seeking personality.
Another one is Goro. He's a petty thief in Naruto fanfiction who has a special skill of being able to blend into the shadows. He steals from local merchants in Konoha. Goro may not seem like a big threat at first, but his actions can sometimes lead to bigger problems, like when he steals important items that are needed for a mission.
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.