It could be a variety of villains. Maybe some of the traditional Naruto villains like Orochimaru or Pain could be in the story and Naruto kills them. Or perhaps in this fanfiction crossover, there are new villains created that are a combination of Naruto - style threats and Justice League - type menaces. It's hard to say exactly without reading the fanfiction, but it would be interesting if it included some well - known Naruto baddies being taken out by Naruto in a new setting with the Justice League around.
Lex Luthor could be a likely villain. He's always devising plans to take down the Justice League, and this time he might have come up with a scheme that almost succeeds, until Batman steps in. For instance, he could create a super - weapon that targets the unique powers of each Justice League member.
Darkseid is another possible villain. He is extremely powerful. He could send his minions to attack the Justice League first, weakening them, and then use some sort of magic or technology to trap them. Batman would then have to find a way to free the League from Darkseid's clutches, perhaps by finding a weakness in Darkseid's power source.
Well, one possibility is that Bakugou is initially frustrated with the hero society in the fanfic. Maybe he feels overlooked or misunderstood. The League of Villains could approach him, promising a place where he can use his power more freely without the restrictions of the hero rules. And he might be tempted by their offer, leading to his joining.
Well, in a lot of such fanfictions, Izuku might be forced to join the League of Villains against his will. They could try to brainwash him, using their various quirks and methods. Maybe they'd want to use his knowledge of hero strategies against the heroes.
Izuku would probably be terrified at first. After all, he's been kidnapped by villains. But then, his hero - like determination would kick in. He might start looking for ways to escape or at least resist their plans.
Well, there could be epic battles. The Justice League would bring their superpowers like Superman's strength and Wonder Woman's combat skills. Gotham villains such as the Joker would try to outwit them with his devious plans. Maybe Batman would be in a tough spot, having to choose between his loyalty to the Justice League and his own way of dealing with Gotham's rogues.
They might be amused. They could find some fanfictions that depict them in ways they never thought of, which might make them chuckle at the creativity of the fans.
For heroic - centric fanfictions, they would likely be disdainful. Since they oppose heroes, seeing stories that glorify heroes would annoy them. They might scoff at the idealized versions of heroes in those fanfictions.
In this fanfiction, Naruto's power is a force to be reckoned with. He has a vast array of ninjutsu skills at his disposal. The Justice League members, on the other hand, are a mix of super - humans and meta - humans. Superman's strength is almost limitless, and Aquaman has his control over the sea. Naruto's ability to defeat villains in this context might put him in a position where he has to prove himself against the Justice League. His shadow clone jutsu could potentially overwhelm some of the League members in terms of numbers, but they have their own unique ways of countering such attacks. It really depends on how the story unfolds and how the powers are balanced in this crossover fanfiction.