I'll probably just have stronger/weaker versions of Evvie not take part in this thread, so if you want to challenge different power levels without an excuse for being so it will just be handled like normal fights without this story to go along with it. If Tre'yan can't handle her physical abilities in a boxing match with her of mid/high tier range then we can say for this match they put her in some arm bands/anklets that reduce her power by subduing a portion of her dragon side. She'd of course still have physical superiority. 

An interesting plotline could be her clones showing up at some point and confusing everyone about who is the real one, or maybe just one of them who truly believes she's the real one. Maybe they can show up in the background every now and than as foreshadowing.