Maybe Sasuke teaches him the Chidori in a moment of camaraderie. And for the Rasengan, it could be an older and wiser Naruto from the future who travels back in time to teach his younger self.
In many Naruto fanfictions, the Chidori - Rasengan combo is often portrayed as an extremely powerful and unique move. It combines the piercing nature of the Chidori with the rotational and explosive force of the Rasengan. Some fanfictions might have Naruto or Sasuke (or both in some cases) creating this combo during a crucial battle against a powerful enemy, like a new Akatsuki member or a rogue ninja from another village. This combo is usually described in great detail, with the lightning - chakra of the Chidori surrounding and enhancing the Rasengan, making it not only more destructive but also having an added effect like paralysis due to the electricity.
It could be Kakashi. Since he's already Naruto's teacher and he knows both techniques. He could guide Naruto in understanding the intricacies of the Chidori, like how to form the lightning - chakra in his hand, and for the Rasengan, he could give more advanced tips on chakra control.
In a fanfiction like this, the plot might involve Naruto struggling to master both techniques. He could start by observing Sasuke use the Chidori and then try to incorporate its lightning - based power into his own jutsu. For the Rasengan, he might have new insights while training, perhaps finding a way to combine it with the Chidori for an even more powerful attack. Along the way, he would face challenges like controlling the chakra flow for both techniques and dealing with opponents who are also after these powerful jutsus.
One creative way is to give it different elemental properties. Instead of just the basic lightning and wind/rotational aspects, they might add fire or water elements to it. For example, if there's a situation where they need to fight an ice - using enemy, they could add fire to the combo to melt the ice. Another way is to have it used in a non - combat way. Maybe Naruto and Sasuke use it to break through a powerful barrier that's not just physical but also has some sort of chakra - based lock on it.
Well, he might start with intense training sessions. Maybe he observes Kakashi closely for the Chidori, and for the Rasengan, he practices over and over again, gradually getting the hang of the chakra control required.
In a more creative fanfic, an ancient ninja who was the originator of the Chidori technique could appear. This ninja could be brought back to life through some sort of magic or jutsu. He sees Naruto's pure heart and decides to pass on the Chidori knowledge to him, believing Naruto will use it for good.
The following are some recommendations for novels where the main character is stronger than the system:
1. The Self-Cultivation of the Male Lead. Author: Wen Ruo Bucheng
2. I'm the Common Villain in the Fictions, by Big Firepower and Small Gun
3. The Number One Strong Control in History. Author: Old Xu
4. Low-Dimensional Revolution, by Fat...
Please note that these novels may only partially meet your needs. You are recommended to search further for more relevant novel recommendations.
It depends on how the author of the fanfiction has developed the plot and the characters. They could have given Natsu some special power - up or a unique situation that makes him stronger than Gildarts. For example, the author might have introduced a new form for Natsu that gives him an edge in combat, or perhaps they've weakened Gildarts in some way for the sake of the story. However, in the original series, Gildarts is extremely powerful, so this is a significant departure in the fanfiction.
In the 'izuku stronger than all might fanfiction', Izuku can be stronger for several reasons. Fanfiction writers often take creative liberties. They may write that Izuku has a deeper understanding of his quirk, One For All, compared to All Might. He could also have additional abilities or support from other characters that contribute to his increased strength. Maybe he has formed alliances with powerful individuals who help him train and unlock new levels of power, enabling him to surpass All Might.