The Superhero Database Classification number, or SHDB Class, is a number that represents the overall 'power' of a character. All traits of a character are used for calculating the Classification.
What it DOESN'T mean
This doesn't mean that a higher class would always beat a lower class character. But the bigger the difference in Class is, the more obvious it is who'll win in a fight.
How is this calculated
( INT^1.3 + (STR*0.5 )^2 + (SPE*0.5)^2 + DUR^1.6 + (POW + (SPS*SPL))^2 + COM^1.8 ) ^ TIER
Super Power Score and Level
Every Super Power has a score (SPS) that is used to calculate the Class. Each Super Power also has 3 levels (SPL). The level is set when connecting that Super Power to a character. The level determines the final score, of the Super Power, being used in the calculation.
first there is strength
Superman failed to hold up an oil rig that weighed 20,000 tons at 2:20
meanwhile Omni-Man held up a mountain that weighed 1,185,246 tons with one arm
next is speed
While Superman was reacting to Flash who was only going mark 6 since there was a deleted scene that showed a bullet moving almost as fast as them
and the Flash movie debunks anyone in Dceu being light speed other than Flash
because it was said if you go light speed you enter this bowl of memories that only Flash can do so Superman is not light speed closer to Hypersonic
Meanwhile Omni-man can resist the pull of a Black Hole at 1:23
which would make Omni-Man faster than the speed of light
and finally there is durability
The Mother Boxes terraform everything on the surface crust of a planet this would make the mother boxes multi-continental
and the blast wiped out the JL including Superman so he can't scale to them
making his durability small country level with the nuke thing on top of that which he took less than half of the blast
Meanwhile Omni-Man is unphased by a punch from Invincible
and Invincible can stop and asteroid and throw it back into space making Mark's strength multi-continental
and since that amount of strength does nothing to Nolan and he can also trade blows with other much stronger viltrumites Omni-Man's durability is around small planet level
So in conclusion Omni-Man is much stronger, faster, and more durable than Superman so if they were to fight it would look something like this
Omni-Man wins
1. Superman’s oil rig feat was when he was just starting to use his powers, he grew much more powerful since then. Also no idea where you calculated the weight of that mountain.
2. Superman shifted an entire tectonic plate in BVS which are quintillions of tons. So Supes is stronger.
3. Omni man never went past the event horizon of the black hole. All he did was watch it from a distance. Even if he did resist the pull of a black hole, it doesn’t matter since Supes also resisted the pull of a singularity when the world engine was destroyed.
4. Flash movie confirmed he’s ftl and Supes can keep up