I always thought that his back story was that he was a Galactic Grunts because in DP, the grunts used Bug-Type Pokemon and that he was one and then possibly he became real strong and decided to quit and one day he was invited to be part of the E4!
I see them using mostly Poison Pokemon (Skutank, Dokurogu, Guregguru, Skunpuu, Golbat), but that would be an excellent plot twist! Inside information for Satoshi-tachi!!!