The villagers of the Land of Waves would surely support Naruto. They have suffered a great deal under Gato's rule, so they would see Naruto as their savior. Also, Sasuke might support Naruto. Even though they have their differences, Sasuke would recognize the need to stop someone as evil as Gato.
In a 'Naruto kills Gato' fanfiction, the plot could start with Gato's continued oppression in the Land of Waves. Naruto, having witnessed the suffering of the villagers, decides he's had enough. He uses his Shadow Clone Jutsu to surround Gato and his men. With a swift combination of Rasengan and his ninja skills, he takes Gato by surprise and defeats him, thus liberating the Land of Waves in a more direct and violent way compared to the original story.
Naruto could use his improved taijutsu skills. He might close in on Gato quickly and land a series of powerful punches and kicks that Gato can't defend against. Since Naruto is quite fast and has good reflexes, he could easily overwhelm Gato in close - combat.
Well, one possible plot could be that Gato has some new evil plan in the Land of Waves. Naruto, having grown stronger, decides he can't let Gato harm the innocent people there anymore. He uses his new jutsu and his quick thinking to outwit Gato's men first. Then, in a final showdown, Naruto unleashes a powerful Rasengan, directly hitting Gato and killing him, thus saving the Land of Waves from Gato's tyranny.
Well, it would be a very dark turn. Gato is a cruel and greedy character. Naruto might be forced to do bad things. Maybe he'd be used for Gato's illegal business. He could be made to fight against his friends in Konoha later on.
If Naruto was adopted by Gato in fanfiction, his character would face a huge transformation. At the start, he could become more withdrawn and distrustful because of Gato's cruel ways. However, Naruto has always been a fighter. So, he would gradually find ways to resist Gato's bad influence. His experience with Gato could also make him more understanding of the hardships that people like Gato's victims face. This would make him more empathetic and determined to make the ninja world a better place once he breaks free from Gato's hold.
There could be a power vacuum left by Adaly White's death. This might lead to different factions in the Gato base area vying for control. Naruto may then have to deal with the aftermath and ensure that a more just leadership takes over.
It could be that Naruto has some sort of intel about Adaly White's weakness. He uses this knowledge to his advantage in the Gato base. He might first disable any guards or traps around Adaly White and then use his chakra - enhanced strength to land a fatal blow.
I'm not sure specifically as there could be many different interpretations. It might be a story where a character named Sakura kills a character named Gato within the context of fan - created fiction. Maybe it involves a conflict between them in a particular fictional universe, perhaps a battle for power or revenge.
First, make sure you understand the basic premise of the 'son of gato' story or the original work it's based on. This will help you better understand the fanfictions. Second, read reviews if available. Other readers' opinions can give you an idea of whether the fanfiction is well - written or not.