Reasoning:
Team leader (Withered Freddy): He's the band leader of the core four and just seemed to fit
Brawler (Withered Bonnie): I would also add Withered Foxy here, since they both seem strong
Weapons Expert (Golden Freddy): It's more like a powers expert than a weapons expert
Brains (Springtrap): He's smart, calculated and manipulative. Do I need to say more?
Medic (Puppet): The Puppet gave life to the other children and is their protector
Speed Fighter (Classic Foxy): he's zoom
Lookout (Mangle): Mangle can climb on the ceiling and has two heads.
Craftsman/Repairman (Henry): It's literally what he does for a living, and he's pretty good at it too.
Child (Child): It's a child.
Cook (Chica): If she knows what good food tastes like, she might know how it's made
Self Sacrifice (Dee Dee): She would summon people then sacrifice herself
Serial Killer (William): He killed at least eleven children and got away with it.
Sharp Shooter (Captain Foxy): Pirates often had little guns on their journeys so he gets one
Gardener (Mr. Hippo): He just seems like the kind of guy
Loveable (Charlie): She's a sweet kid who protects the others
Paranoia (Shadow Bonnie): He just fits here in my opinion.