I think Kurama and Kagome would be an interesting pair. Kurama, with his calm and intelligent demeanor, and his ability to use plants and nature - based powers in combat, could learn a lot from Kagome's knowledge of spiritual powers and the Sacred Jewel. Kagome, on the other hand, could be intrigued by Kurama's complex past as a demon - turned - good. They could exchange ideas about how to deal with demons and use their respective powers more effectively. And their more gentle personalities compared to some of the other characters in their respective shows could lead to some really interesting character - development - focused interactions.
Hiei and Sesshomaru would be a fascinating combination. Hiei is a short - tempered but extremely powerful demon from Yu Yu Hakusho. Sesshomaru is a proud and powerful full - demon in Inuyasha. They both have a sense of superiority in their own ways. Hiei because of his strength and Sesshomaru because of his noble birth. If they were to meet, there would be an intense power struggle at first. But as they face a common enemy, they might start to see the value in each other's skills. Hiei's speed and his Jagan eye could be a match for Sesshomaru's Bakusaiga and his speed as well. Their interactions would be full of tension and grudging respect.
Well, perhaps the Sacred Jewel from Inuyasha somehow gets linked to the Spirit World in Yu Yu Hakusho. Kagome and Inuyasha follow the strange energy trail to the Spirit World. There, they meet Yusuke and Kuwabara. They find out that a powerful spirit in the Yu Yu Hakusho world is corrupted by the dark energy of the Sacred Jewel fragments. So they all have to work together to purify the spirit and restore balance to both worlds. The differences in their fighting styles, like Inuyasha's swordsmanship and Yusuke's martial arts - based spirit attacks, would make for some cool battle scenes.
Ichigo and Yusuke would be a really interesting pairing. They both have that hot - headed, determined nature. Ichigo with his Hollow powers and Yusuke with his demon powers could create some epic fight scenes together. They could also learn from each other's experiences in the spirit world and how they handle their powers.
One interesting plot could be that Yusuke from Yu Yu Hakusho gets transported to the world of Inuyasha. He teams up with Inuyasha and his group to fight a common enemy, like a powerful demon that is causing chaos in both their worlds. Yusuke's spirit energy could be a great asset in battles against the demons in Inuyasha's world.
Yusuke's Rei - gun from Yu Yu Hakusho could be combined with Inuyasha's Tessaiga. For example, Yusuke could use his Rei - gun to enhance the power of Inuyasha's Tessaiga slashes. This would create a more powerful attack against demons. The combination of their raw power would be a force to be reckoned with.
Well, a really common one is a training - based crossover. Imagine Yusuke training Rin in some of his more unorthodox fighting techniques from Yu Yu Hakusho. Or perhaps the opposite, with Rin teaching Yusuke about demon - slaying weapons. Another popular concept is a friendship - centered crossover. Since both shows have themes of friendship and loyalty, fans might write about the characters becoming fast friends. They could go on adventures together, sharing their different perspectives on the spirit and demon worlds. And of course, there's always the idea of a love - interest crossover, where a character from one show has an unexpected romantic encounter with a character from the other, though this is less common in these types of action - based shows.
It's really hard to say. Naruto has some extremely powerful characters like Naruto himself with his Nine - Tails chakra and Sage Mode. But in Yu Yu Hakusho, characters like Yusuke at his Mazoku form are also incredibly strong. It might depend on how the crossover is written. If the power - up systems are combined in a certain way, it could be a character who manages to blend both types of powers most effectively.
I think Naruto and Levi would be really interesting. Naruto's positive and determined attitude would contrast with Levi's more stoic and no - nonsense personality. They could learn a great deal from each other. Naruto could teach Levi about the power of friendship and believing in oneself, while Levi could show Naruto some of his amazing combat skills and discipline.
Another plot could involve the Soul Reapers from Bleach and the Spirit Detectives from Yu Yu Hakusho having to exchange their skills and knowledge to deal with a common enemy. For example, the Soul Reapers teach the Spirit Detectives about the use of zanpakuto, while the Spirit Detectives show the Soul Reapers how to better use their spiritual energy in a more physical combat - oriented way. This could lead to some really interesting character interactions and development.
I think Ben's Heatblast and Thor would be an interesting combination. Heatblast can generate intense heat and fire, while Thor has his lightning powers. They could create some really powerful elemental attacks together.
Carly and Jade could be really cool together. Carly is sweet and friendly, while Jade is edgy and a bit of a troublemaker. Their interactions would be full of contrast. Carly might try to soften Jade a bit, and Jade could introduce Carly to a more rebellious side of life in Hollywood Arts.