Another plot could be that Kurama's human form has a special ability that is unique even among his demon abilities. This ability attracts the attention of both good and evil forces, and he has to figure out how to use it without causing chaos.
Perhaps Godzilla in human form falls in love with a human. But he is constantly worried about endangering the person he loves because of his true nature. He has to battle his own kind, who see his relationship with a human as a betrayal, while also trying to keep his human love interest safe from the chaos of the kaiju world.
A possible plot is that Kurama's split personality actually has a soft side. This side of Kurama starts to merge with Naruto's kinder nature, creating a new personality within Naruto that is extremely empathetic. This new personality tries to find peaceful solutions to conflicts, which surprises both Naruto's friends and enemies. Another plot could be that Naruto's split personality caused by Kurama starts to have its own set of memories, memories that are related to Kurama's past and the ancient history of the ninja world, and Naruto has to figure out what these memories mean and how they can help him in his present situation.
Well, in fanfiction, Kurama's human form could be a really imposing figure. He might have long red hair, just like his fox form's fur color, and bright, piercing eyes. Maybe he'd be tall and muscular, with a sort of wild, untamed look about him, still carrying that powerful presence that he has as a tailed beast.
One idea could be a story where the Bakugan in human form have to blend into human society while hiding their true identities. They could face challenges like going to school or getting a job without revealing their Bakugan nature.
One idea could be that the Kyuubi in human form becomes Naruto's mentor in secret. He teaches Naruto some ancient and powerful jutsu that were lost over time. This could give Naruto an edge in battles and also deepen his connection with the Kyuubi.
One plot idea could be Amaterasu living among humans in her human form and using her divine powers secretly to help them. For example, she might use her ability to control nature to end a drought in a small village. Another could be her forming a friendship with a human artist who, unknowingly, starts to paint pictures that are prophetic due to her influence. A third idea is that she has to hide her identity from a group of hunters who are searching for any signs of the divine, as they believe the gods are causing chaos.
One plot idea could be Kurama and Kushina teaming up to protect the Hidden Leaf Village from a new, powerful enemy. They could combine their unique abilities, like Kushina's strong chakra chains and Kurama's immense power, to fend off the threat.
Often in fanfictions, Kurama's human form and Naruto have a more complex relationship. They could argue at times, especially when Naruto wants to take risks that Kurama thinks are too dangerous. But at the same time, they also share some really tender moments. For instance, Kurama's human form might comfort Naruto when he's feeling down about his past or his struggles with the village. They would have a deep bond that goes beyond just being a jinchuriki and a tailed beast.
One plot idea could be Naruto gradually learning to fully control the Kyuubi's power in a more conscious way. He could discover new abilities that are a blend of his own ninja skills and the Kyuubi's raw power. For example, he might be able to use the Kyuubi's chakra to create illusions that are more powerful and realistic than normal genjutsu.
A really interesting plot could be Acnologia in human form forming an unlikely alliance with the Fairy Tail guild. He could be on a quest to redeem himself for his past dragon - related atrocities and the guild helps him in some way. This could lead to many adventures where he has to use his human skills and not just his dragon powers.