Assuming they are the same size...
RWBY: The Knight has the speed and hax to contend with pretty much most of the cast, their strength depends on how great a yield shaking the entire kingdom would be (CB? MCB? Town level? City level?), which would be enough to deal with most of the cast except maybe the Maidens and maybe some of the stronger Grim. If there's a pre-Radiance light related reaction feat I somehow missed, they could take everything up to the Brothers.
Mass Effect: Reapers are town level/city and MHS? In that case the Knight is at a speed disadvantage, although they have good hax and (possibly) enough power.
Zelda: Isn't Zelda moon/planet level? That sounds like too much for pre-EOG Hollow Knight (unless there is something regarding the Dream that I'm forgetting).
Nasu/Fate: No idea, but based off what I heard about stuff like Space Ishtar, they won't clear even end of game.