In such a fanfic, the Avengers' diverse powers would clash with Darth Vader's formidable Force abilities. Iron Man could use his high - tech suits to try and outmaneuver Vader's lightsaber attacks. Captain America might lead the charge with his shield against Vader's dark side - enhanced combat skills. It would be an epic battle of good from different universes against Vader's Sith - influenced evil.
It really depends on how you write it. If it's Anakin at his peak before turning to the dark side, he has a lot of raw power and potential. But Vader has years of experience as a Sith Lord. So, it could go either way.
Luke Skywalker could be another key character. Since he is Vader's son, his presence could add an interesting dynamic. He might be the one who somehow triggers the battle between Anakin and Vader, or he could be in a position to influence the outcome of their fight, perhaps by appealing to the remaining good in Anakin or by facing off against Vader himself in a three - way struggle.
One interesting plot twist could be that Darth Vader is actually related to one of the Avengers in some way. Maybe there's a long - lost family connection that changes the whole dynamic of the fight. Another could be that the power source of the Infinity Stones somehow combines with the Force, creating a new and unexpected power that either Darth Vader or an Avenger has to control. It could also be a plot twist where the Avengers think they've defeated Vader, but he actually uses a Sith technique to possess one of them and turn the tables.
One idea could be a what - if scenario where Anakin in his pre - Vader state somehow gets a glimpse of his future as Vader. He could then fight against the dark side within himself that would turn him into Vader. Another could be a time - travel plot where Vader is sent back to face Anakin, and Anakin has to decide whether to accept his possible future or fight against it.
In my opinion, if the Avengers were to win in an 'avengers vs darth vader fanfic', it would be through teamwork. They would need to combine their powers effectively. For example, Doctor Strange could use his magic to counter Vader's Force powers while the others engage in physical combat. But Darth Vader is not to be underestimated. His combat experience and his ability to use the Force for both offense and defense are remarkable. If he were to win, it would likely be by isolating the Avengers and taking them out one by one. So, again, it's a very uncertain outcome.
A fan fiction could also explore a parallel universe where Anakin and Darth Vader are two separate entities that co - exist. They are forced to fight not because of Anakin's fall, but due to some external force that wants to see the two most powerful Sith - like beings battle it out. This could lead to an exploration of their different fighting styles and the power dynamics between them.
A common mistake is getting the technology wrong. In Star Wars, the technology has a certain look and function. If a fanfiction has blasters working like modern - day guns with no energy bolts or has spaceships that defy the known physics of the Star Wars universe, it vitiates the story. For example, making the Millennium Falcon fly in a way that's completely at odds with how it's supposed to operate based on the movies and extended universe.
To vitiate Star Wars fanfiction, one could mess with the iconic settings. Say, changing the look and feel of the Death Star to something completely unrecognizable and not in line with the Star Wars aesthetic. Or by creating really flat and uninteresting relationships between characters. When the interactions lack depth and emotion, like if Han Solo and Chewbacca's friendship is portrayed as dull and uneventful, it can vitiate the overall quality of the fanfiction.
A really cool 'Star Wars Vitiate' fanfic could be a story that takes place in an alternate universe where Vitiate has a change of heart. It could show his struggle to resist the dark side and how that affects the balance of power in the galaxy. This would be a very different take on the character and would offer a unique perspective on the Star Wars lore.