Naruto would likely rely on his speed and powerful jutsu. His Rasengan could be a major weapon against Darth Nihilus. However, Darth Nihilus has the ability to drain life force. If he manages to get close to Naruto, it could be a big problem for Naruto. But Naruto's chakra reserves are vast, so he might be able to withstand the initial attacks.
A possible fanfiction could involve a fusion of their powers. For example, Naruto discovers a way to combine his chakra with the strange energy that Darth Nihilus wields. This new power could be used to either save the world from a greater threat or to bridge the gap between the two universes. Or perhaps Darth Nihilus, in his search for power, tries to steal Naruto's chakra, but Naruto's bond with his friends and the Nine - Tails gives him the strength to resist and turn the tables on Darth Nihilus.
Darth Vader could emerge victorious. His mastery of the Force gives him an array of abilities such as telekinesis and mind control. He could potentially use these to disable Naruto before he has a chance to launch a major attack. Also, Vader's lightsaber skills are top - notch. If he can get close to Naruto, he could deliver a fatal blow. And in a one - on - one situation, without the help of his friends, Naruto might find it difficult to counter Vader's unique powers.
Naruto would have the upper hand. Naruto's training with Jiraiya and other great ninja has made him a formidable opponent. His Rasengan and other signature moves are extremely powerful. Darth Bane, while a powerful Sith, is not used to the type of energy (chakra) that Naruto wields. Also, Naruto has the ability to tap into the power of the Nine - Tails at will, which would give him a significant boost in combat against Darth Bane.
I really like 'Darth Nihilus: The Lost Years'. This fanfiction fills in the gaps of what Darth Nihilus might have been doing during his less - known periods. It has some really interesting battles and interactions with other Sith Lords that are not in the official canon but feel very much in - spirit with the Star Wars universe.
It's hard to say for sure. Darth Vader is extremely powerful with his connection to the Dark Side of the Force. He can choke opponents from a distance and has great combat skills. But the Avengers are no pushovers. Captain America is a great strategist and fighter, and Black Widow is skilled in espionage and combat. In fanfiction, sometimes the outcome might be a draw where they realize they have more in common than they thought and end up teaming up against a greater threat instead of fighting to the death.
One common theme is the clash of different power systems. Since Harry Potter has magic and Darth Nihilus has the Force, exploring how these two interact is a popular theme. For instance, in many fics, they might test which is stronger or how they could be combined.
If the fight got really intense and out of hand, it could also make Naruto feel pressured to choose sides. However, Naruto being Naruto, he would most likely try to find a way to reconcile them instead. This would show his growth as a person and his ability to rise above family disputes.
Another plot point is his interaction with powerful magic - users in a crossover. In a world like Harry Potter, Darth Nihilus's power would be a huge disruption. The way his power might be countered or even enhanced by magic is a fascinating plot point. The story could explore if the wizards and witches could find a way to stop his life - draining abilities or if he could learn to use magic to his advantage.
One great Darth Nihilus crossover fanfiction is 'Darth Nihilus in the Star Trek Universe'. It explores how his unique power of draining life would interact with the different species and technologies in Star Trek.
Darth Nihilus was a powerful Sith Lord. He had an insatiable hunger for the Force. He could drain the life force from entire planets, leaving them desolate wastelands. His appearance was rather menacing, with a mask covering his face. His power made him a feared figure in the Star Wars universe.