Suggested by iKnowledge Be’lakor is one of those monsters that Fiona would want to be avoiding right from the start. She isn’t typically a fighter but is able to conquer her fears and keep moving as needed. I don’t think fighting someone like Be’lakor would cause her to freeze up anymore but she has no way to realistically land any damage on him. That’s what will ultimately spell her defeat her. Be’lakor wins.
Suggested by iKnowledge Sasori is a powerful ninja. He had to be in order to join the Akatsuki after all. He has a lot of good attack strategies from close to long range. That said, Fiona isn’t really much of a fighter so either way he can steal the win. She is great at surviving and can possibly dodge him for a little while but there isn’t really a route to victory for her. Sasori wins.