Well, to determine if JL 50 is a real story, we need to look at its source, the details presented, and any available background information. But as of now, with just the name, it's impossible to tell.
Superman is extremely powerful on his own. His powers are almost god - like. But the Avengers have a lot going for them too. For example, Iron Man has his high - tech suits which can adapt to different threats. Captain America is a great strategist. In a fanfiction, it could depend on the circumstances. If it's a fight in an environment full of kryptonite, the Avengers would have an advantage. But in a normal battle, Superman's power might be too much for the Avengers to handle all at once.
Well, Superman might use his super strength and flight to take on the Avengers. Maybe he'd go up against Thor first, with their super strength and lightning powers clashing. It could be an epic battle.
In a 'naruto vs avengers fanfiction', there could be a lot of chaos. Naruto's ninja skills like shadow clones and rasengan would be pitted against the Avengers' superpowers. For example, Naruto might try to use his speed to dodge Thor's hammer throws. It would be a battle of different fighting styles and power sources.
Perhaps there is a powerful artifact that both Spiderman and the Avengers are after. They end up in a conflict over it. Spiderman, with his street - smart ways, tries to outwit the Avengers and get the artifact for himself, believing he can use it for good in his own way.
It's really hard to say who would win in a 'naruto vs avengers fanfiction'. Naruto is extremely powerful with his ninjutsu and his ability to summon large toads. But the Avengers also have their own powerful members like Captain America's leadership and combat skills, and Thor's godly powers. It could go either way depending on the situation.