One idea could be that Naruto discovers he has a special power that only activates at night. For example, he might be able to communicate with nocturnal animals and they help him in his ninja missions. Another could be that at night, Naruto's appearance changes in a way that gives him an edge in stealth, like his hair turns black to blend in with the darkness better.
A great plot twist could be that Naruto's night - turning is actually part of a prophecy that no one knew about. The village initially thought it was a bad thing, but it turns out it's the key to saving the ninja world from a greater threat. Maybe it's related to an ancient evil that only emerges during the day, and Naruto's new form at night is the only counter to it.
If Naruto turns into a Digimon in a fanfic, it could also be due to a curse or a dark magic. He might start off confused and disoriented in his new form. However, being Naruto, he would quickly adapt. He could form an unlikely alliance with some Digimon characters. His Digimon form might have some sort of unique ninja - like attacks that are a combination of his original jutsu and the digital powers. For example, his Shadow Clone Jutsu could be transformed into a digital clone attack where the clones are made of digital energy.
In a fanfic, Naruto turning into a Pokemon might also lead to some comical situations. Imagine Naruto, now as a Pokemon, trying to communicate with his friends in Konoha. He might have to use Pokemon sounds and gestures at first, causing a lot of confusion among his comrades. But eventually, they figure out a way to understand him, and it becomes a fun adventure for everyone.
It could also be that Naruto has a misunderstanding. He might misinterpret some actions of Konoha as being malicious towards him or his friends. As a result, he decides to oppose the village. However, as the story progresses, he realizes his mistake and instead works with Konoha to resolve the issues that led to the misunderstanding in the first place.
At first, Naruto would likely be very confused and hurt. He has always craved family love and acceptance, so this sudden turn would be a huge blow. He might try to plead with his family, asking them to believe him and give him a chance to explain.
One possible plot could be that Naruto's transformation into a female fox brings out new aspects of his ninja abilities. Maybe the female fox form has a special connection to nature-based jutsu, allowing Naruto to control plants or communicate with animals in ways he couldn't before. This could lead to new adventures where he has to use these unique skills to protect the village from a new threat, like a powerful dark wizard who is draining the life force from the forest.
One possible plot twist could be that Naruto, while in his Kyubi form, loses control completely and starts to attack his friends. This would create a huge internal conflict for him when he comes back to his senses. Another could be that his transformation into the Kyubi gives him new abilities that are not related to just brute strength, like the power to communicate with other ancient beasts. Also, perhaps the transformation is not permanent, but rather fluctuates based on his emotions, leading to some really tense moments during battles or important interactions.
One possible plotline could be that Naruto is constantly shunned and mistreated by the village despite his efforts to protect it. This continuous rejection could gradually turn his heart cold and make him seek revenge. He might start using his powerful jutsu against those who once wronged him, like attacking the Hidden Leaf's leadership.
Well, a cool plotline could be Naruto using her new female form to her advantage in missions. Maybe she can infiltrate places more easily as a girl. Also, there could be a plot where Naruto has to hide the fact that she was once a boy from some new characters she meets. This could lead to some really funny or tense situations as she tries to keep her secret while still being herself.