((Picture not mine! Credit to artist))

Hilbert was born and raised in Mistralton City. He was educated at a small school located in the local gym. The gym leader before Skyla, a grass type specialist, took a special interest in Hilbert, who he recognized as a trainer with a lot of potential. The gym leader retired before Hilbert received his starter at age 14. Skyla, one of his friends from school, became gym leader and gave him a Rufflet to start off with. Hilbert went on a journey around Unova and ended up collecting all eight badges. When he was 15, he challenged the Elite Four, but was demolished. After some coaching from his ex-teacher, he went to challenge the Elite Four again. He lost to Alder. Eventually, Hilbert gave up and began training his team for the Battle Subway instead of the Elite Four. He became a regular there. The Battle Subway was also where he met Hilda, Cheren and Bianca. After the events of BW, Hilbert continued training his Pokémon for Competitive battling. He wasn't present during BW2 as he was visiting Johto for a battling tournament. In the years leading up to Sun and Moon, Hilbert continued honing his battling skills. He eventually will get  a job offer from Skyla and will be Mistralton gym trainer and battle coach.