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.
But the pinnacle of nonsense are the following examples:
1. Mind Control Resistance (on the highest level). Is that why he was successfully brainwashed by Ultear?
2. Enhanced Senses Smell,Hearing etc. (on the highest level). This should only be assigned to Fairy Tail characters that are either dragons or Dragon Slayers. Jellal isn't one of them.
3. Enhanced Memory. (on highest level) That's probably why he was discovered without memories by the Oracion Seis...
Well, I forgot superpowers should be added randomly to characters...
Or maybe it became some sort of contest as to who can add the biggest pile of bullshit?