Twenty years have passed since Alola's first Pokémon Champion had defeated the Alolan Pokémon League. The Aether Foundation had been forced to abandon their offshore Pokémon sanctuary after the Ultra Beast incident involving the Alolan Champion and the Aether President, Lusimine. The man-made island was quarantined off from all exploration and deemed hazardous to both Pokémon and humans. It has remained uninhabited since that time and none dare not go near it for fear of an Ultra Beast whisking them away to a far-off realm, never to return. There have been rumors and stories passed around by the frequent sailors and locals of the Alola Region regarding the old, abandoned Pokémon sanctuary. Tales of mysterious lights, mad scientists, unholy experimentation, and abdominal creatures born from these experiments. The general public disregards these as hoax. Because who would continue the Aether Foundation's research knowing the dangers it poses, let alone attempt to use ground zero as a testing site. However… There are some tales that have their truths…
Deep within the underground laboratories of the abandoned Aether Foundation Pokémon sanctuary, A man wearing a torn lab coat stands in front of a glowing capsule filled with an unknown green fluid. The adjusts his cracked green glasses as his expression of madness shown in the green glow of the container. "Finally, after all these years!" He grinned triumphantly as he stared into the sole occupant of the glowing container. An Eevee, its fur shone as a snowy white even while suspended within the container and obscured by the its green glow. The man rushed over to the barely functional laptop which was connected to the Eevee's capsule and he scanned the vital signs of his new creation for the fifth time. "I have finally created a Pokémon capable of battling and defeating Ultra Beasts that could even rival the Legendary Pokémon of our world! I, Branch Chief Faba, will finally be recognized for my genius!" The mad man cackled at the thought of finally becoming the president of the Aether Foundation, despite the relocation and possible disbandment of the Foundation itself. "All I had to do was dig into some old files regarding Dr. Fuji's genetic research and improve upon it from there!" He frowned as he recalled the reports regarding Mewtwo's awakening and consequential escape. Thinking that using just one legendary Pokémon's DNA as the sole base of the creature was the cause of such an act of rebellion. Faba believed that since Eevee was possibly a much more docile and malleable base, that it would less of a hassle to handle. "Years of traveling across many regions, from Kanto to Kalos. Collecting the DNA of the most powerful Pokemon of every type and bonding it them into one subject took years of my life away from me." Faba rants as he leaves his computer and returns to his precious creation with madness still dripping from his expression. "But all that time was worth it!" The former branch chief cackles madly and turns away from the tank before continuing his madness.
Meanwhile, within the gestation tank, the small, man-made Pokémon began to stir. "W-where… Am I? What am I? W-why am I here?" The Eevee's mind reeled at his first thoughts as he began to gain consciousness. He struggled to open his eyes as green fluid clouds his sight and its glow brings pain to his sensitive eyes. The Eevee tried to breathe only to be impeded by the fluid surrounding him, causing him to panic! "Can't breathe! Must get out!" Suddenly, dark shadows surround the white furred evolution Pokémon and lash out at the glass holding him within the container. The glass shatters, causing the container's contents to spill onto the cold laboratory floor along with the man-made Pokémon as the shadowy nightmares danced around the small Pokémon, frightening him. It was not just the dark creatures that caused him fear, but the strange creature with a look of pure madness, wearing white which was attempting to grab him. "What are these creatures!? Go away!" The white Eevee screeched as the creatures surrounding him once again lashed out enveloping the creature in white. He then made a run towards an open doorway. Rushing through multiple halls and up several staircases in an absolute panic before finally emerging out into the dock. His head whipped around to see the hall he came from crawling wall to wall with the nightmarish shadow creatures. The evolution Pokémon backed away toward the edge of the dock as his nightmares drew closer until, he slipped and fell into the dark waters.
Meanwhile, within the Gathering Hall for the Council of Legends, Arceus sits. Watching the plight of this new life before speaking. "And so, the wheels of destiny begin to turn…" The Alpha Pokémon rises to his hooves and goes to summon the Council for an emergency session.