One reason could be a new magic source. Natsu might discover a powerful magic that surpasses Gildarts' abilities.
The writer may have personal reasons for making Natsu stronger. They might be a huge Natsu fan and want to see him in a more dominant role. Additionally, it could be a way to subvert the expectations of the original series. In the original, Gildarts is a very high - level mage, but in the fanfiction, Natsu could be stronger due to some sort of divine intervention. Maybe a god - like entity bestows Natsu with extra powers that make him more powerful than Gildarts. This could also be related to a prophecy or some ancient magic that only Natsu can access, which gives him the edge over Gildarts.
Perhaps the author wants to show Natsu's potential. By making him stronger than Gildarts, it emphasizes how much growth Natsu can achieve. Another reason could be a change in the story's setting. If the fanfiction is set in a different world or time, the power balance could be altered. Also, it could be for the sake of a unique plot device. For example, Natsu has to be stronger to defeat a new and extremely powerful villain that Gildarts couldn't handle.
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.
Well, one possibility is that Gildarts could share some of his powerful magic techniques with Natsu. Since Gildarts is a very experienced wizard, he might see the potential in Natsu and offer some tips on how to better control his fire magic, which is similar to Igneel's. Maybe he could also tell Natsu some stories about his own adventures that would inspire Natsu to become even stronger.
Natsu could try his all - out offensive with his most powerful fire attacks. He might start with his Fire Dragon's Roar and then quickly follow up with a combination of punches and kicks enhanced with his fire magic. Another strategy could be to use his environment. If they're in a place with flammable materials, he can set them on fire to create distractions or additional sources of power for his attacks.
One reason could be Naruto's unwavering determination. He has always been able to push past his limits. In many battles, his willpower has been a key factor in his victory. Another could be his unique chakra nature and the amount of chakra he has at his disposal. Naruto has a vast reserve of chakra, which gives him an edge in long - drawn battles. Also, his ability to form strong bonds with others might contribute. These bonds could potentially unlock new powers or give him the strength to fight against Kaguya.
In fanfiction, Naruto can be stronger than Madara for multiple reasons. Some authors might want to subvert the expectations set by the original story. They could give Naruto unique abilities like the ability to manipulate time, which would clearly put him above Madara in terms of power. Additionally, it could be a way to bring in crossovers. For instance, if Naruto gains powers from another fictional universe, he could easily be made stronger than Madara. Moreover, the author may simply want to explore a scenario where Naruto is the most powerful character, and making him stronger than Madara is a step towards that.
In the fanfiction, Gildarts could meet Natsu and Igneel during a time of crisis. Maybe their town is under attack. Gildarts would immediately jump into action, and Natsu would follow suit, with Igneel guiding Natsu from the side. Gildarts might be impressed by the way Natsu and Igneel work together, as if they share a single mind. They could communicate without words, and Gildarts would try to learn from their unique bond. After the battle, Gildarts would offer to train Natsu further, seeing his great potential enhanced by his connection with Igneel.
One reason could be the variety of his abilities. Naruto has a whole range of jutsu like the Rasengan and Shadow Clone Jutsu. In fanfiction, these could be made extremely powerful. For instance, if his clones could multiply infinitely and each had the power of the original, that would be a huge advantage.
Well, Naruto has had the advantage of learning from many great shinobi over time. He also has a unique bond with his friends which could potentially give him more strength. Minato, on the other hand, had a shorter lifespan to develop his powers. Naruto has had more time to grow and surpass his father in strength.
One reason is Naruto's vast chakra reserve. His Uzumaki heritage gives him an almost unlimited supply, which can be emphasized more in fanfic. So he can keep going in a fight longer than Kakashi.
One reason is that Naruto has the Nine - Tails' chakra. In fanfic, this power can be further enhanced or manipulated in ways that make him far more powerful than Sasuke. Another reason could be his more outgoing personality. He might be able to form alliances more easily, leading to him having more resources and power - ups at his disposal.