Suggested by JordyPresto0418 Kairi has finally obtained mastery over her Keyblade. I expect this will lead her to using quite a lot of advanced abilities in the near future. That said, the games haven’t had a real chance to show off much of her skill yet. Meanwhile Rey had a whole trilogy to temper her abilities with a Lightsaber. Right now the difference in their combat abilities is key. Rey would quickly take Kairi down in a battle of blades and her Force abilities further extend the advantage to Rey. Rey wins.