Ruby is a likely winner. She has her powerful scythe, great speed, and strong leadership skills. Her ability to quickly analyze a situation in battle gives her an edge. Weiss also has a good chance. With her Glyphs and powerful summoning abilities, she can control the battlefield. Blake is another one. Her speed and shadow - cloning ability make her a tough opponent. And Yang with her super strength and ability to take a hit and then counterattack fiercely could also be a top contender.
In my opinion, Pyrrha would be a very likely winner in a RWBY tournament fanfiction. She was already an extremely skilled fighter before her untimely death. Her martial arts expertise combined with her polarity semblance made her a force to be reckoned with. Another character could be Cinder. Despite being a villain, she has shown great power, with her ability to control fire and her strategic mind. Mercury and Emerald also have unique abilities that could potentially lead them to victory in a tournament setting.
Natsu. He's got incredible power and determination. His ability to eat fire and use dragon - slayer magic gives him an edge. He's not afraid to take risks and he's always ready for a fight, which would be very useful in the various tasks of the tournament.
Cinder Fall could be a likely betrayer. She's already a villain in the original series, and in a fanfiction, she could pretend to be an ally to one of the RWBY members only to betray them at a crucial moment, perhaps leading them into a trap set by Salem.
Weiss is also popular. Her ice - based powers and her growth from a somewhat uptight character to a more team - oriented one is interesting. In the tournament, her elegant fighting style and strategic use of her powers are always a highlight.
Ruby is a likely candidate. She's already a skilled fighter with her scythe, and her eagerness to learn new techniques would make her adapt well to Santoryu. Her speed and agility could be enhanced with the three - sword style.
Ruby is an obvious choice as she has that lead - character feel. Her naivete and determination are traits that can be paralleled to Dorothy. She would be the one to lead the group through the strange world of Oz.
Obviously Naruto would be one of the main characters as the title implies he is being trained. And then, the RWBY characters like Ruby, Weiss, Blake and Yang would also be main characters since they are the ones doing the training.
Well, Naruto for sure. His immortality gives him a unique place in the story. From RWBY, Yang Xiao Long could be a main character. Her brash and confident fighting style would create an interesting dynamic with Naruto. Blake Belladonna, with her mysterious past and cat - like abilities, might also be a central figure. Her more reserved nature compared to Naruto's open - heartedness could lead to some great character development moments. And of course, Ruby and Weiss as mentioned before, would also be important in shaping the story around an immortal Naruto in the RWBY world.
Obviously, Ruby, Weiss, Blake, and Yang would be main characters. They are the core of RWBY. Ruby with her speed and scythe skills would be crucial in any fight. Weiss, with her ice powers, could freeze some of the terrifying enemies from 'The Evil Within'.
Most likely Ruby, Weiss, Blake, and Yang from RWBY will be main characters. Since it's a RWBY crossover, they are the core of the RWBY universe and would be the ones to enter the 'heaven' in the fanfiction.
Obviously, Harry himself is the central character. Hermione and Ron would also likely be involved. They are Harry's best friends and usually play important roles in his adventures. Hermione with her intelligence might help Harry figure out strategies for the tournament tasks, and Ron with his loyalty would be there to support Harry.