Valkyrie and Valhalla are a mother and son duo.

Valkyrie was the battling Gardevoir of a Hoenn pokemon master and had an egg with one of her trainer's pokemon. However, Valkyrie discovered that her trainer wanted to trade the Ralts that was going to hatch out, and so stole the egg and ran away. 

Valkyrie's own egg was from Hoenn but she hatched AFTER her trainer had moved to the Alola region. She has been living there ever since. 

Valhalla and his mum met two released pet pokemon, a Lucario called Anubis and a Gallade called Lancelot, while they were hiding in the forests of Melemele Island. Not long after that, the trio joined up with another group of three lost pokemon: A Shiny Gardevoir named Crystal, a Shiny Gallade called Diamond, and a Shiny Lucario named Star. 

The six pokemon became good friends and helped two other legendary pokemon, Mewtwo and Mewthree, to save the islands.

Valkyrie travels a lot with Crystal, who has become her best friend, so Valhalla often stays with Star who is like an older sister to him. Lancelot and Anubis both have interests in Valkyrie, but she is leaning more towards the Gallade in terms of who she'll settle with in the future.

Valhalla is a bubbly, loveable, and innocent little Ralts. His mother is kind, cheerful, gentle, protective, and funny Gardevoir who cares for and trusts everyone around her without a second thought. Valkyrie has an almost untameable love for food and hot drinks, as well.

VALKYRIE

VALHALLA

THE LOVELY PAIR

(Art not by or belonging to me obviously, just for appearance reference)