Tosh said:
Broly from Movie 8 was able to destroy a Galaxy. He solo's.
He didn't. He destroyed a fraction of a Galaxy over time, and even that could be seen as inconsistent due to many surrounding stars in said Galaxy were shown later on. It'd also logically require Multi-Solar System level power to wreck a Galaxy as quickly as he did, yet general scaling from the anime contradicts this (since SPC is at the very most a Solar System buster).
Regardless of where you stand on the Solar System argument for Cell, Broly should still be vastly above New 52 Superman in power and durability (Small Star - Star level VS Large Planet level). The only problem for Broly is that Superman is fast enough to blitz him (flew from Pluto to Earth in seconds and from the Edge of the Universe to Earth in 2 months), debatably comparable, if not far greater, stamina (bench pressed the Earth for 5 days without the Sun to re-energise him) and is far more intelligent than Broly. Even though he'd be oneshotted if hit, Superman's got what it takes to avoid this happening should he play things right.