Relic Pokemon are a generation of older pokemon primarily thought to be a long-gone species but have recently begun to pop up out of nowhere, as the character is told by Regan, after reaching the point of myth. They first appeared during the War on Hawthorne, as she'll tell you. they almost never enjoy being owned by Trainers, though the first one you receive is oddly willing to come along.
Like in Pokémon Black and White when you’re given a free elemental monkey, your first relic Pokemon is based on the started picked. It’ll join you happily so you don’t need to catch it. However, if you are wanting a certain nature, gender, or Ability, make sure you have a free slot since, as of 0.1.2, you’re unable to view its stats right away.