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.
Here is what it said:
1. Ichigo, 2. Yhwach, 3. Soul King, 4. Kenpachi, 5. Aizen, 6. Shunsui, 7. Mayuri (!!)
Yeah, why not. Maybe the A.I. forgot a few characters who should've been included, like Gerard ?
On the other hand, we cannot possibly know how well Shunsui would've performed against Gerard. Maybe Shunsui could've won.