There's also the possibility that a new character created through the Xros of a Digimon and a ninja could be the most powerful. Imagine a Digimon that has absorbed Naruto's chakra and can use it to enhance its attacks. This new hybrid character could have unique abilities that neither the Digimon nor the ninjas possess on their own, making it a very powerful entity in the fanfiction.
Arceus from Pokemon and Omnimon from Digimon are both extremely powerful. Arceus is like a god in the Pokemon world, creating everything. Omnimon is a powerful Digimon formed by the fusion of WarGreymon and MetalGarurumon. If they were in a crossover, it's really hard to say who would be more powerful. It might depend on the situation and how their powers interact.
It could be Kirito. He has a lot of combat experience from SAO. If he teams up with a strong Digimon like Omnimon, he would be extremely powerful. His sword - fighting skills combined with Omnimon's attacks would make them a formidable force in any battle.
Sasuke might also be a strong contender. His Sharingan gives him an edge in combat and perception. In a Star Wars setting, he could use his Sharingan to predict his opponents' moves in lightsaber duels or even sense the presence of the Force in a unique way. And his thirst for power could drive him to master both ninjutsu and the Force quickly.
It could be Sailor Moon herself. Her powerful magic and ability to transform could give her an edge. She has the power of the Silver Crystal which is extremely potent. When combined with the powers of a strong Digimon, she would be nearly unbeatable.
Omnimon could also be a very powerful partner for Naruto. Omnimon is a super - powerful Digimon resulting from the fusion of WarGreymon and MetalGarurumon. Naruto's ability to make friends and work in teams would be perfect for handling Omnimon's complex nature. Together, they could take on any enemy in the fanfiction world.
The novelty. Combining Digimon Xros Wars with other Digimon series or even non - Digimon elements in a crossover creates something new and exciting. It allows fans to see their favorite characters in different scenarios and interacting with unexpected others.
It could be Naruto. His ability to harness and control large amounts of chakra is already very powerful. If he were to also gain the ability to use the Force, he would be nearly unstoppable. He could use his Sage Mode along with the Force to sense danger from afar and attack with great force.
Naruto and Agumon would be a great pairing. Naruto's energetic and fearless nature would mesh well with Agumon's loyalty and eagerness to fight. They could both learn from each other's determination in battle.
Sasuke and Renamon would also make a great pairing. Sasuke's brooding and intense nature could be complemented by Renamon's calm and collected demeanor. Renamon's intelligence and combat skills could match Sasuke's Uchiha abilities. They could have some intense training sessions together, where they both learn new techniques from each other.
It could be Naruto. His ability to access the Nine - Tails' chakra gives him an incredible power boost. He also has a lot of combat experience and his rasengan could potentially be as powerful as a well - aimed lightsaber strike. His never - give - up attitude would also make him a force to be reckoned with in the Star Wars universe.