An aberration possesses the following traits (unless otherwise noted in a creature's entry).
Darkvision 60 feet.
Proficient with its natural weapons. If generally humanoid in form, proficient with all simple weapons and any weapon it is described as using.
Proficient with whatever type of armor (light, medium, or heavy) it is described as wearing, as well as all lighter types. Aberrations not indicated as wearing armor are not proficient with armor. Aberrations are proficient with shields if they are proficient with any form of armor.