A great plot could involve Naruto being brought into the world of the Grand Magic Games against his will. At first, he's completely out of his element. But as he starts to understand the rules and the power of magic, he discovers new ways to use his chakra. He might enter a tournament event where his speed and agility, enhanced by chakra, give him an edge over his magic - using opponents. And in the end, he could end up changing the very nature of the Grand Magic Games with his unorthodox style.
One possible plot could be that Naruto and his friends enter the Grand Magic Games by some strange magic portal. They have to learn new magic skills quickly to compete. Naruto might use his shadow clone jutsu in a creative way combined with magic, like having clones do different magic spells simultaneously.
An interesting plot could involve an OC who is actually from a long - lost guild that has a deep connection to the origins of the Grand Magic Games. The OC enters the games with the secret mission of uncovering the truth about their guild's past. As they compete, they start to notice strange things going on behind the scenes that seem to be related to their guild's history. They have to balance their search for the truth with their performance in the games.
If Naruto joins the Grand Magic Games in fanfiction, he would bring his unique fighting style. His chakra control could be adapted to deal with magical attacks. He could also learn new magic skills from the other participants. His positive attitude would likely influence the overall atmosphere of the games as well.
One idea could be a character from a different guild who has a hidden power enters the Grand Magic Games and disrupts the usual dynamics. For example, a young mage with the power to control time but doesn't know how to fully use it yet. This could lead to some really cool and unexpected battles and alliances.
Perhaps a character from a small and unassuming guild has a hidden power that is awakened during the Grand Magic Games. This power could be related to an ancient magic that was thought to be lost. The character then has to learn to control this power quickly while also dealing with the pressure of the Games and the attention it brings from other guilds.
It could be Orochimaru. He might have found a way to enter the Grand Magic Games world and is using his dark jutsu to control some of the magic users. He wants to use the power of the games to become even more powerful and immortal.
Well, one possible plot twist could be that Natsu returns with a new, super - powerful form that no one expected. Maybe he has mastered a long - lost magic during his absence.
One idea could be Sasuke using his Sharingan to analyze the magic patterns of opponents in the Grand Magic Games and develop new combat strategies. He might form an unlikely alliance with a magic user who has a unique ability that complements his skills.
One idea could be Gildarts having a secret mission during the Grand Magic Games. Maybe he's investigating a dark force that's trying to disrupt the games from the shadows.
Perhaps Lucy gets transported to a different dimension during the Grand Magic Games. In this dimension, the rules are all messed up and she has to use her wits and the help of some strange new allies she meets there to find her way back to the real Grand Magic Games and continue competing. It would be a story full of adventure and discovery.