Well, a cool plot for this crossover fanfiction could be that the Pokemon trainers are summoned to the Inuyasha world to help stop a new evil that is related to both the Pokemon world and the Inuyasha world. Maybe a villain has found a way to combine the power of the Shikon Jewel with a powerful Pokemon artifact. The trainers and their Pokemon have to work together with Inuyasha and his friends. Some Pokemon might evolve during the intense battles, and the Inuyasha characters could learn about the concept of evolution in the Pokemon world, which could be a fun aspect to explore.
I think Pikachu and Shippo would make an adorable pairing. They are both small and cute, but also have their own unique powers. Pikachu's electricity and Shippo's fox magic could be combined in interesting ways during battles. Also, Brock and Miroku would be an interesting pair. Brock is always chasing after girls, and Miroku has his own, well, wandering hand problem. They could bond over their, um, interesting relationship with the opposite sex while also sharing their knowledge of healing (Brock with Pokemon and Miroku with his spiritual healing).
One idea could be that Sephiroth somehow gets transported to the feudal era of Inuyasha. He might initially be seen as a great threat due to his power. But as the story progresses, he could form an unlikely alliance with Inuyasha and his group against a common enemy, like a powerful demon that is even more menacing than any they've faced before.
A popular one is 'The Meeting of Paths'. This fanfiction focuses on a situation where Inuyasha and Sesshomaru meet under different circumstances than in the original series. It has great characterizations, and the way the two interact and gradually change their views of each other is really well - written.
One idea could be that Sakura, with her medical ninjutsu skills, ends up in the Feudal era of Inuyasha. She could help treat the wounds of the villagers who are often attacked by demons. Inuyasha might be initially suspicious of her strange powers but gradually come to respect her as she proves her worth in battles and in healing the injured. For example, when Inuyasha gets seriously injured in a fight against a powerful demon, Sakura's medical skills could be the key to saving him, which would change his view of her.
Another interesting concept is that the Jewel of Four Souls has some sort of connection to a powerful and rare Pokémon. The characters from both worlds then have to team up to either protect or destroy this connection, depending on whether it's a threat or a potential boon.
Power and growth. Both Inuyasha and Bleach have characters with different levels of power. In crossovers, often a character from one series has to adapt and grow in the other's world, facing new challenges that test their power.
Characterization can be tough. Each character from both series has their own distinct personality. The Avengers have their own dynamics, and Inuyasha has his own temperamental nature. When bringing them together, the writer has to ensure that the characters stay true to themselves while also developing new relationships. For instance, Captain America's sense of justice might clash with Inuyasha's more self - centered approach to fighting at first.
One possible plot could be that Inuyasha somehow gets transported to the Twilight world. He might initially be confused by the modern settings and the presence of vampires and werewolves. Bella could mistake him for a new type of supernatural being. And Inuyasha, with his sword and combat skills, could get involved in the ongoing feud between the Cullens and the werewolves in Forks.
One common theme is the clash of different cultures. Naruto's world is more about ninja villages and modern - ish (for a fantasy world) structures, while Inuyasha's is a feudal era world. So when they cross over, there's often exploration of how these different cultures interact.