It's hard to say for sure without reading it, but it could include the main characters from One Piece like Luffy, Zoro, and Nami. Maybe some new characters created by the fanfic writer as well.
Well, Luffy would probably be one of the main characters as he is the protagonist of the One Piece series. Other members of the Straw Hat crew like Sanji, Usopp, and Chopper would also likely be involved. Additionally, we might see some of the important non - Straw Hat characters like Shanks or Ace (if the story is set before his death). And of course, there could be new and interesting characters created specifically for this fanfiction to drive the plot of the 'War of the Best'.
The Straw Hat Pirates would probably be the main characters. Luffy, with his determination and leadership, would be right in the middle of the action. Zoro, with his powerful swordsmanship, would be crucial in battles. Nami could use her knowledge of the weather to gain an advantage. And other members like Sanji, Usopp, and Chopper would also play important roles.
I think 'One Piece War of the Best Fanfiction' could center around a war that has the best elements from the One Piece world. It could involve the clash of ideologies among the pirates. For instance, some pirates might be fighting for freedom in a different way compared to Luffy's crew. And there could be a complex plot where different alliances are formed and broken during this war, with the fate of the One Piece world at stake.
The plot could involve a new and dangerous enemy emerging, threatening the Strawhat Pirates' quest for adventure. Or it could be an internal struggle among the crew members that leads to a challenging situation. There could also be a hidden treasure that everyone is vying for, causing tensions to rise.
In many Whitebeard War fanfictions, Marco the Phoenix stands out. His ability to heal and his loyalty to Whitebeard are remarkable. Also, Squard is often a memorable character. His betrayal and then possible redemption can be a very interesting arc within the fanfiction. He adds an element of internal conflict within the Whitebeard Pirates which makes the story more complex.
In XCOM War of the Chosen fanfiction, some of the best characters are often the soldiers. They have unique personalities and skills. For example, a sniper with a backstory of being a hunter before joining XCOM can be really interesting. Their ability to stay calm under pressure and make those long - range shots is crucial in the story.
Most likely the main characters would still be the Straw Hat crew. Luffy would surely be a central figure as he is in the original One Piece. His carefree and determined nature would probably be adapted to fit the gamer - style story.
Zoro is also a popular character in fanfiction. Some writers focus on his backstory and how it might be further developed in the Netflix - inspired fanfiction. They might show his training in more detail, or create new challenges for him that test his loyalty to the crew and his strength as a swordsman. For instance, he could face an opponent who uses a new type of swordsmanship that he has to quickly learn to counter.
Often, there are the soldiers themselves. They could be the common foot soldiers, the ones on the front line facing the enemy directly. These are the guys who experience the heat of battle, like the rifleman who has to take aim and fire at the approaching enemy forces.
In this fanfiction, the main characters might include a young and inexperienced ment called Leo. He's eager to prove himself in the war. Then there's the mysterious Sage, an old ment who seems to know a lot more about the war and the ments' history than he lets on. There's also a female ment named Nia, who is a skilled fighter and is constantly challenging the traditional roles of ments in the war.
I'm not sure specifically as it depends on the particular fanfiction. It could be original characters created by the author, or it might reimagine existing characters in a new 'salvation war' context.