This is a hard question to answer because unlike the IG, 'beating' the UN doesn't require a set level of power or w/e -- it requires a ludicrous insertion of plot-induced-stupidity, and/or character-haxx.
Franklin Richards, for example, might be capable of beating Galactus, but he could not survive the UN. Flip side, Mr. Immortal certainly cannot beat Galactus, but he can survive the UN.
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"I am tired of Earth. These people.
I am tired of being caught in the tangle of their lives."
Cosmic Cubes
Classic Starbrand (Quasar who only had a FRACTION of it was wiped out by the UN but reconstructed himself despite interference from Oblivion and Eon).
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..even the outer hells are indifferent matters for they bow only to potent and archaic Nodens.