^He is but size wouldn't be much of an issue here. I'm not going to comment on who wins because both have poorly defined power limits. On one hand Beyonder's power was basically being more powerful than anything while he CA's ability was to counteract anything, up to and including Mandrakk's story-eating powers.
Originally posted by Omega Vision
To be fair the LT probably couldn't have beaten Mandrakk either. LT's story isn't very strong.
But LT could have done what Mandrakk was going to do in Final Crisis: Superman Beyond 1/2 on a whim.
I mean the Presence never directly intervened, so his feat really isn't that impressive.