Take Shirou vs Gilgamesh. These are, probably the furthest possible gaps in power that you can imagine in the setting, and yet, Shirou wins. This isn't because Shirou is stronger than Gilgamesh, it's because Shirou happens to have the tools to counter Gilgamesh.
Almost any conflict in Fate is going to work along these lines of, "Who has the counter to the other" --> "Who thematically answers the other better" --> "Who has the greater Mystery/Concepts going on"
