Sasuke could also be a main character. His relationship with Naruto is so crucial to the whole story, and there are always more things that can be explored about him, like his journey to atone for his past actions. And also Sakura, she has her own story arc and skills, and her relationship with Naruto and Sasuke is also an important part of the story.
Naruto himself is very likely to be one of the main characters. After all, he is the central figure of the Naruto franchise.
There is also a possibility that some of the new generation characters like Boruto could play a significant role. Although it's a side story, it might be used as a way to bridge the gap between the old Naruto story and the new Boruto series, so Boruto could be involved in some way to show how the legacy of Naruto and his friends is carried on.
It could still be Naruto himself. Since he's the central character in the original series, many fanfics would likely continue to build on his story.
Obviously, Naruto would be the main character. Since it's about him being the new Kyuubi. And his friends like Sasuke, Sakura, Kakashi would also be important characters. They would likely be involved in how they react to Naruto's new state and how they support or oppose him.
Sakura would probably be a side character. She could be the one who checks on Hinata's health during her pregnancy if that's part of the story. Shikamaru might also be there, helping Naruto with some of the strategic planning for the village while also giving him relationship advice. And Boruto and Himawari would be important side characters as their children, adding a family - centered aspect to the fanfiction.
Obviously Naruto would be one of the main characters. Since it's related to the Juubi, Sasuke could also play a major role. They've always been connected to the main threats in the Naruto universe. And if it's a crossover, maybe some characters from other popular anime could be involved, like Goku from Dragon Ball. He's super powerful and his presence could add an interesting dynamic to the story.
I'm not sure exactly as it may vary from the original, but likely there are characters representing the two opposing sides, similar to Tony and Maria in the classic 'West Side Story'.
Peppa and George are most likely to be the main characters as they are in most of the Peppa Pig stories.
Obviously, Harry Potter himself would be the central character. Then, Voldemort would be a major figure as he is the main representative of the Dark Side. Bellatrix Lestrange could also play an important role as she is one of Voldemort's most loyal followers. She might be the one to initially tempt Harry or guide him into the ways of the Dark Side.
Well, obviously Naruto himself would be the main character. There could also be his friends like Sasuke and Sakura, who might be involved in the interactions between the two Narutos. Maybe they are confused at first by seeing two Narutos, but then they help them figure out what's going on.
I'm not entirely sure as I don't have specific details about it yet. But it's likely that the main character from the original Pearl Boy story will be there.
The main characters in the 'fgo new years side story' are a mix of old favorites and potentially new arrivals. The player's own Master character is crucial as they lead the way through the events. Servants like Mash, who is a staple in the Fate/Grand Order story, is likely to be involved. Additionally, Servants associated with luck or celebration, such as certain Chinese or Japanese - themed Servants given the New Year context, could be main characters. And sometimes, even Servants that have been in the background in the main story might get a chance to shine and be more central in this side story, adding new dimensions to their characters and relationships within the game.