Sasuke could be an interesting addition. His brooding and powerful nature would add an element of mystery in Kim's world. He might initially be distrustful of Kim and her crew, but as the story progresses, they could learn from each other. Maybe he could teach Kim some advanced ninja techniques in exchange for her helping him with something from her world.
Kim Possible would also be a great character in this crossover. Her ability to handle various situations and her quick thinking would be valuable in the Naruto universe. She might be able to come up with unique strategies to deal with the ninja villains, using her own set of skills and gadgets.
Ron and Shikamaru could have some great interactions. Ron's laid - back but sometimes surprisingly insightful nature could play off well against Shikamaru's intelligent and lazy - seeming demeanor. They might start off not understanding each other but end up becoming good friends as they face challenges together.
Well, Danny Phantom has the ability to phase through objects and fly at high speeds, which is really cool. Ben 10 can transform into so many different aliens, each with their own unique powers. And Kim Possible is super athletic and has all those useful gadgets. However, I think Ben 10 might be the most powerful in a crossover. His Omnitrix gives him access to a wide variety of powers that can be used in different situations. For example, if they were in a fight underwater, he could transform into an alien that is adapted to aquatic environments. But again, it's all about how the story is written and what challenges they face.
Definitely Harry Potter and Kim Possible themselves. Harry has his whole wizarding world experience and his fight against dark magic, and Kim has her crime - fighting skills and high - tech gadgets. Their different worlds and abilities would create a really interesting dynamic as they try to understand each other and work together.
Kim Possible herself. She's a strong, independent character. In a fanfiction with Danny Phantom, she could be the one to teach Danny a thing or two about being a hero without superpowers (at least in the traditional sense). Her determination and resourcefulness would be a great contrast to Danny's more impulsive use of his powers at times. Plus, seeing her react to the supernatural elements of Danny's world would be fascinating.
Ron and Ron Stoppable could be a hilarious pairing. They both have their insecurities but also their brave moments. They could get into all sorts of comical situations together, like accidentally mixing up a wizarding potion with one of Kim's high - tech gadgets and creating something completely unexpected.
Definitely Gaara. His ability to control sand is unique. In the Borderlands 2 setting, he could use his sand to protect his teammates from the various attacks, like from the psychos or the Loader Bots. His transformation into Shukaku could also be a very powerful and visually striking element in the crossover.
I think Gintoki would be the most interesting. His laid - back and cynical nature would contrast so much with the more idealistic Naruto. He would constantly be making sarcastic remarks about Naruto's ninja -isms and the whole concept of being a hero. But at the same time, he would also be secretly impressed by Naruto's unwavering determination. And seeing Gintoki try to use Naruto's ninja tools or techniques in his own wacky way would be really entertaining.
Naruto would be really interesting. His never - give - up attitude would make him stand out in the spooky FNAF world. He'd probably be the one to charge headfirst into danger, whether it's facing the creepy animatronics or trying to solve the mysteries of the place. He could also try to befriend the animatronics if he thought they were being controlled against their will, just like he did with some of his enemies in the Naruto world.
It could be Ben himself. Imagine him using his alien forms in the Naruto universe. His Heatblast form could be really useful against ice - based jutsu, and Four Arms could take on some of the physically strong ninja. He would bring a whole new element of power and chaos to the Naruto world, and his reactions to the different cultures and powers in Naruto's world would be interesting to explore.
Sasuke could be really engaging in this scenario. His cold and calculating nature would be a contrast to the chaos of the zombies. He might see the zombie outbreak as an opportunity to gain more power or find a way to use the situation to his advantage against his enemies in the Naruto world. And his Sharingan could potentially have some new abilities when dealing with the undead.