Darkseid ain't what he used to be. Back in the day, old Uxas was far more powerful than how he is now.
But where on the overall power scale was he exactly?
More to the point, where does the line of "ones who can beat pre-Crisis Darkseid" begin?
My gut says maybe somewhere between Classic Odin and Galactus, so maybe ... Celestials? I know this Darkseid beats any solo version (non-IG/non-HOTU) of Thanos.