Definitely Ben Tennyson himself. His ability to transform into various aliens would add a whole new dynamic to the Star Wars universe. Also, characters like Darth Vader would be great. Imagine the confrontation between Ben in one of his powerful alien forms and Vader with his lightsaber and the Force. Another interesting character could be Yoda. Yoda's wisdom and his unique view of the Force could interact in an interesting way with Ben's more action - based alien powers.
Luke Skywalker would be a really interesting character to include. He's on a journey to become a Jedi and learn about the Force. Ben could join him on this journey and use his alien forms to help Luke in various situations. For example, if they encounter a dangerous beast, Ben could transform into an alien with the right abilities to defeat it. Additionally, Han Solo could be in the fanfiction. His roguish charm and piloting skills could pair well with Ben's abilities as they go on adventures together across the galaxy.
The Emperor would be a fascinating addition. His thirst for power and control could lead to some intense conflicts with Ben. Ben's alien powers might be the only thing that can stand up to the Emperor's dark side powers and his vast resources. Also, Ahsoka Tano would be great. Her combat skills and her own complex relationship with the Jedi Order could interact with Ben in an engaging way. Maybe she could learn from Ben's different ways of using power through his alien forms.
One interesting crossover could be Ben using his Omnitrix to transform into an alien that has Jedi - like powers. For example, a species with enhanced mental abilities similar to using the Force. Another could be a scenario where the villains from Ben 10 team up with the Sith in Star Wars to take over both universes. Maybe Vilgax and Darth Vader working together, with Vilgax's brute strength and Vader's mastery of the dark side of the Force creating a really formidable alliance.
Well, you could have a fanfiction where the Galactic Empire somehow gets hold of the Omnitrix. Then they try to use it to create super - soldiers. Ben, of course, has to break into their strongholds to get it back. Or perhaps there's a story where Ben is mistaken for a new type of Force - user because his alien transformations seem to give him powers similar to the Force in some ways. He then has to navigate the complex politics of the Star Wars galaxy while trying to clear his name.
One interesting crossover could be Ben using his Omnitrix to transform into an alien that has the power to use the Force. For example, he could transform into a species that has telekinetic abilities similar to Jedi powers. Another could be the Ben 10 characters getting involved in the Galactic Civil War in the Star Wars universe. Maybe they help the Rebels fight against the Empire using their unique abilities.
Definitely Luke Skywalker. He could bring his Jedi wisdom to Earth and teach people about the Force. Han Solo would also be great. His roguish charm would be fun to see on Earth. And of course, Darth Vader. His imposing presence would create a lot of drama.
Han Solo and a Skaven from Warhammer. Han's roguish charm and ability to get out of tough situations could be pitted against the devious and sneaky Skaven. The Skaven's underhanded tactics and Han's quick thinking would make for some really entertaining encounters as Han tries to outwit the Skaven in various situations across the two universes.
Definitely Luke Skywalker. His character has so much potential for development during the Dark Empire. He could be struggling with the resurgence of the dark side and his own temptations. Another interesting character is the new Emperor. You can explore his motives and his use of the dark side power. And Leia Organa is also great to include. She could be leading the New Republic's efforts against the Empire and also dealing with her own family issues.
One idea could be that Ben uses his Omnitrix to transform into alien forms that have unique abilities to survive in the Star Wars universe. For example, a heat - resistant alien to withstand the heat of Tatooine's deserts or a species with enhanced senses to navigate the dangerous jungles of Kashyyyk. Another idea is that the Galactic Empire somehow gets hold of the Omnitrix and tries to use it for their own evil purposes, leading to Ben having to team up with the Rebel Alliance to get it back.
One interesting idea could be exploring Ben's internal struggle in more depth. Maybe his journey to fully embrace the light side and overcome the dark influences that have been plaguing him. It could also involve new relationships he forms during this awakening process, like with characters who help him see a different path.
Gwen could be really interesting. She could have developed different powers in a different time period that Ben discovers when he travels back. Also, Grandpa Max in his younger days would be cool. He might have been involved in some secret time - traveling adventures that Ben uncovers. And Vilgax from different points in time could add a lot of drama. Maybe a younger Vilgax who is still learning and more vulnerable, or an older, more powerful Vilgax from a far - off future.
Ben Tennyson is definitely an interesting character to include. His ability to transform into different aliens gives a lot of possibilities for the story. Finn the Human is also great. His adventurous spirit and his sword - fighting skills can add action to the fanfiction. Jake the Dog can be really fun too, with his shape - shifting abilities. And of course, Princess Bubblegum, her intelligence and leadership can bring a different dynamic to the story.