Pokemon have always lived on the continent of Avalon, long before even recorded history.
2,000 years ago, in the area where the kingdom of Aether now is, a group of Pokemon arrived from the moon via a meteor impact. They quickly adapted to the customs of the surrounding kingdoms and created their own, which became one of the most advanced civilizations on the continent. They also had a treasure known as the Celestial Stone; an object of unimaginable power and, like all objects of power, other people sought to claim it for themselves.
1,000 years after that, there was an enemy who everyone thought they could trust who attacked during the coronation ceremony of the new king. The new king managed to use the Celestial Stone's power to seal it away for the next millennia; however, it came at a cost. Fairy-typing was sealed away along with the stone. However, this still was not enough to stop the enemy from burning the kingdom to the ground and slaughtering almost everyone in the largest genocide in recorded history on the continent of Avalon. Though the other countries defeated the enemy after that, the old kingdom never recovered. To this day, no one trusts the savage foe who devastated Aether; their lands so well guarded by the bordering countries that even the name of their nation has been lost to the annals of time.
Near 1,000 years past that great slaughter, a king from a land unknown to those of Avalon arrived upon the shores of the ruined kingdom of Aether. From there, he and his people rebuilt and reached out to all those around them, guided by a prophecy whispered by many. Undaunted by the obstacles and threats that abounded the lands they adopted as their own, the kingdom has begun thriving once more. It seems these these foreigners have arrived just in time, for perhaps they will be the key to discovering the cause of a growing chaos that lurks like darkness throughout this great land...