One possible interesting plot could be Obito revealing his true identity to the Akatsuki members. It would create a huge shock and change the dynamics within the group.
Minato might also be a prominent character. As their teacher, he can influence the way Obito and Kakashi interact. In some fan fictions, he could be the one to help them resolve their differences or provide some crucial information about their past that changes their current situation.
Some fanfictions might explore the emotional aspect of their fight. For example, how their past friendship affects the battle. Maybe Kakashi hesitates to strike a fatal blow because of their shared history.
It could be the main protagonist if the story is written in a way that the character manages to control and utilize all the Akatsuki powers effectively. With the combined powers, they would have a vast array of abilities at their disposal, making them extremely formidable.
Well, it could be that there's a plot device like an ancient artifact. This artifact might have the power to draw out and combine the Akatsuki powers. The Akatsuki members themselves might be tricked into contributing their powers to this artifact, and then the protagonist or an antagonist gets hold of it and gains all those combined powers. It's a common trope in fanfiction to use such magical or mysterious items to bring about extraordinary power combinations.
In some fan fictions, there might be a plot where Obito has a change of heart before a major battle with Kakashi. He could start to question his motives and the path he has chosen, leading to a very intense and emotional confrontation with Kakashi that is more about ideology than pure combat.
One interesting scenario could be Naruto having to face multiple Akatsuki members alone and using new, unexpected jutsu. For example, he might combine his Rasengan with Sage Mode in a unique way to counter their attacks.
Konoha vs Akatsuki in a Naruto fanfic is a really interesting concept. Konoha represents the forces of good and order. They have a lot of resources and support from the village. Akatsuki, on the other hand, is a group of outcasts with unique and often extremely powerful abilities. In a fanfic, the outcome could be swayed by many factors. For instance, if the fanfic focuses on the power of friendship and teamwork in Konoha, they might prevail. But if it's more about the individual might of Akatsuki members, then Akatsuki could come out on top. Also, the presence of certain characters like Sasuke and his choices could greatly impact the result.
One key battle could be Naruto vs Itachi. Itachi is a very powerful Akatsuki member and Naruto has his own strong powers. Another might be Kakashi against Kisame. Kakashi is a skilled Konoha ninja and Kisame is a formidable Akatsuki member. Also, the fight between the Hokage of Konoha and the leader of Akatsuki would be crucial.