The Jade Sisters

Backstory
Mia, although being the youngest of the Jade Sisters, seemed to get the most attention from the other sisters than anyone else. However, her older sister Maya, being a Shiny Pokemon, got more attention than the other sisters. Some Pokemon and other creatures were jealous, and this lead to an unknown figure attempting to kill the Jade Sisters, which eventually brought Mia's life to an end.

Death
A strange creature, reported to be wearing a deep blue hoodie seemed to have something against the Jade Sisters, and had enough of them. The creature then proceeded to kill off the Jade Sisters, and one other. Mia was the second victim, dying at a young age.