Well, one possibility is that they could use their future knowledge to prevent some of the tragedies that occurred in the original timeline. For example, they might be able to save some characters who died. They could also change the relationships between different ninja clans, making the ninja world more harmonious. And perhaps they would train harder in the past to become even more powerful ninjas in the future.
Their relationships would likely become stronger. They would have to rely on each other more in the unfamiliar past environment. For example, Naruto might look up to Kakashi even more as he sees how much Kakashi has grown and changed. Sasuke might be more open to the idea of teamwork as they face challenges together in the past.
Obviously, Kakashi is one of the main characters since it's about his time travel. Minato is also a central figure as he is part of Team Minato that Kakashi travels back to be with. And of course, the other members of Team Minato like Obito and Rin are likely to be important characters as well.
There's also 'Back to the Beginning: Team 7's Time Travel'. Here, Team 7 travels back to a crucial point in the Naruto universe's history. They end up changing some small things which have big consequences later. It's full of action and the character development is really well - done.
Obviously, the main characters would be the members of Team 7, which include Naruto, Sasuke, and Sakura. Naruto, with his determination and never - give - up attitude, would be a key player in dealing with the challenges of the past. Sasuke, with his powerful ninja skills and complex personality, would also play an important role. And Sakura, who has grown into a strong kunoichi, would contribute with her medical and combat abilities.
Kakashi's abilities would likely be enhanced in the past. He has all the knowledge and skills he's gained in the future. So, his combat skills would be more refined. His Sharingan would be even more powerful as he would know better how to use it. He might also be able to teach his younger self some new jutsu that he learned over the years.
A really cool plot might be that Kakashi time travels and discovers a hidden conspiracy in the past that was related to Team Minato. He then has to work with his past comrades, including Minato, to uncover the truth and prevent a great disaster that he knew about from his own time.
One good plot could be Kakashi going back in time and using his future knowledge to prevent the death of his comrades in Team Minato. For example, he might be able to stop Obito from getting crushed in that rockslide. Another plot could involve him trying to change the course of the war by influencing key decisions made by his team. He could also go back and try to train himself better in the past, using the skills he's learned in the future.
In a Sakura and Kakashi time travel fanfiction, they could end up in the past during a major war. Kakashi would be a great asset with his Sharingan and combat skills. Sakura, on the other hand, could help the wounded soldiers. Their presence in the past could change the outcome of the war. For example, they might be able to save some important characters who were supposed to die. This would then lead to a completely different future when they return to their own time.
Kakashi would be really interesting. He has a lot of past experiences and knowledge. In a time - travel scenario, he could use his wisdom to guide Team 7 through different historical events. He might also have some personal moments, like seeing his old friends or mentors in the past. His sharingan could also play an important role in understanding the new situations they find themselves in during the time travel.