Goku in Ultra Instinct mode is extremely powerful. He has superhuman speed, strength, and can dodge attacks effortlessly. However, Luffy also has his own set of amazing abilities like his Gear Fourth form which gives him enhanced speed and power. But I think Goku would win because his combat skills and power level are just on a different scale compared to Luffy.
One possible plot could be that there is a rift in the multiverse that brings Goku and Luffy together in a strange new world. They initially misunderstand each other and start to fight. As the fight progresses, they both realize that there is a greater threat at hand that is causing the rift. So, they team up, with Goku teaching Luffy some of his combat techniques and Luffy showing Goku the value of friendship and loyalty in a different way.
In a fanfiction battle, perhaps the fight begins with Naruto trying to talk to Goku first, to understand his intentions. Goku, not really understanding Naruto's world, just wants to test his strength. So he attacks without warning. Naruto quickly enters his Nine - Tails Chakra Mode to defend himself. The fight then escalates as Goku powers up further. The two exchange blows, with Goku's punches creating shockwaves and Naruto's attacks leaving marks on the ground. As the fight goes on, they both start to respect each other's power and skills, and it becomes more of a battle of wits as well as strength.
It depends on the rules set in the fan - fiction. If it's a battle based on strategy, Issei might have a chance. He has shown to be quite cunning in his battles. But if it's a pure power - based fight, Goku has the upper hand. His years of training under various masters and his Saiyan heritage give him an edge. Also, Goku has experience fighting opponents much stronger than himself and finding ways to overcome them.
Well, it's really hard to say for sure. Ultra Instinct Goku is extremely powerful with his god - like reflexes and insane combat skills. But Fairy Tail characters also have some very strong magic. If we consider Goku's speed and strength, he might have an edge. However, some Fairy Tail mages could potentially use powerful spells to counter him. So it could go either way depending on how the fanfiction is written.
Well, it could be really exciting to imagine Goku's reactions. He might be shocked by some of the out - of - character portrayals in the fanfiction. Maybe he'd laugh at some of the comical scenarios that fans create for him in those stories.
Well, in some fanfictions, the battle might start as a misunderstanding. Spiderman could be in Gotham chasing a bad guy who has a connection to New York and Batman mistakes him for a new threat. In this case, Spiderman would try to explain himself but Batman, being the brooding detective, might not listen. Then there are scenarios where the battle takes place in a neutral location like an abandoned warehouse. Here, both of them have to rely on their skills and resources. Spiderman would use his webs to create obstacles and Batman would use his gadgets to break through them. Also, there could be a scenario where they team up against a greater threat first and then due to a clash of egos, they end up fighting each other.
In a 'Naruto vs Ichigo' death battle fanfic, there are several important factors. Naruto's chakra control and his ability to learn new jutsu quickly are important. He can also use nature transformation, which can give him an edge against different opponents. Ichigo's spiritual pressure is a major factor. The more he can control and increase it, the more powerful he becomes. Also, his ability to sense and react to his opponent's attacks is crucial. Another factor is their experience in battle. Both have faced many tough opponents in their series, and that experience will play a role in how they fight each other.