(Does not evolve.)
Cryptidex: Comaclysm (comet + cataclysm)
Disaster Quartet: Impact
Comaclysm is one of the Disaster Quartet, legendaries born out of the fear of human-created and cosmic disasters. Comaclysm is theorized to have been involved in the First Hoennese Weather Crisis in antiquity, where a meteor impact awakened a Kyogre and Groudon that caused untold devastation in the Hoenn region already affected by firestorms and tsunamis from the meteor.
In modern day, the Selene series of missions to Gaia's moon attracted the attention of various pokemon-like entities from low orbit, high orbit, the moon itself, and even as far as Ares and the asteroid belt. Dragon-types are the protectors of Gaia from Cosmic-type threats, and so Dragon Clan adepts and a Mega Rayquaza again took up that duty to drive Comaclysm away. It escaped capture and is believed to be in a low-aura mode beyond Selene's orbit. Poorly edited images of purported sightings of it via telescope are common internet hoaxes.
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Design notes: asteroids, Ezekielian angels
Quite proud of the HUD photo for this one.