Moofs (Power levels)
The Gaiaphage, a being dependent on radioactivity, causes things in the FAYZ area to mutate. Some of these mutations takes form in humans and form abilities that are out of the ordinary, extensions of things and generally can be used for great destructive potential. Diana Ladris, one of these moofs, has the power to measure other people's power, using her intelligence and wit she comes up with a system to compare powers among people using bars, like cellphone reception bars. The analogy is that the stronger your power is, the more bars you have. The cellphone tower in this idea is the Gaiaphage, which shares a field between the said moof and itself. But if a moof were to die the Gaiaphage would lose the moof's said power and vice-versa.
Powers range from finding things about other people to defying the laws of physics. The most powerful thing/person in the FAYZ is Little Pete (in body form), ironically he was never measured. The second most powerful being is the Gaiaphage. If the Gaiphage had fully discovered all of its powers and matured enough, it would have probably been off the scale. Before Duck Zhang severely weakened the Gaiaphage, it would have been almost impossible to defeat without the help of Little Pete.
The amount of so-called 'bars' you have also roughly translates to the importance you have, however this does not apply to normal people. For example, Caine and Sam have a turf war that pretty much lasts the whole book, and they are both king/mayor and have a lot of followers. On the opposite end of the scale is Virtue Brattle-Chance who does not appear to play much of a role in the story, except of course for warning Sanjit of Caine's evil intentions.
Caine Soren (Telekinesis)
Sam Temple (Super-heated light and balls of light)
Gaia Soren-Ladris* (All known powers)
* When measured shortly after birth.
Brianna (Super speed)
Dekka Talent (Ability to manipulate gravity)
Penny (Ability to manipulate someone's fears/an illusionist)
Andrew (Ability to create shockwaves)
Taylor (Teleport anywhere she has been)
Two Bars Edit
Computer Jack (Superstrength)
Astrid Ellison (ability to see someone's importance(she no longer has that power as of Hunger))
Diana (Ability to measure other people's power)
Bug (Camouflage, ability to turn almost invisible)
Bette (ability to create floating lights)
Virtue (Ability to sense another person's inner self)
Peter Michael "Little Pete" Ellison (Reality manipulation, teleportation, dream manipulation etc.) - Assumed off scale
Duck Zhang ( Ability to control his density)
Hunter Lefkowitz (Ability to create microwaves[possibly 2 or 3 bars])
Jill 'The Siren' (when she sings nobody can move)
Fire Girl (Ability to shoot liquid fire, sticks to walls)
Sinder(Ability to grow plants at a faster rate)
Lana Arwen Lazar (Ability to heal herself and others)
Emily (ability to warp space around her)
Toto (Able to tell the truth from lies) (Likely a 1 bar)
Darla (Walk through walls)
Brittney Donegal/Drake Merwin (Indestructible(however can be destroyed by Sam's super-heated light))
Fredrico ( can leap from wall to wall)
Note:There are also many unknown characters that have powers.