Doug is an NPC controlled by Keys2tkingdom. He is the Foreman of the Clavis' Pokémon Ranch and is responsible for the care of Ren's mon when they are "in storage". Doug is also responsible for the swapping out of Ren's mons as needed.
Doug is five years older than Ren, and the two have know each other since Doug got a part-time job as a Ranch hand. As such, Ren treats Doug as more of a friend than employee. Doug is also quite intelligent, have a degrees in pokémon breeding and nursing, a skill-set that would lead him to eventually be promoted to the Foreman of the Clavis' Pokémon Ranch. Doug is also the one who advises - and sometimes even makes - the training and feeding regimens for Ren's team.