Ultra Megalopolis

Ultra Megalopolis (Japanese: ウルトラメガロポリス Ultramegalopolis) is a city situated in Ultra Space that can be accessed from Alola through an Ultra Wormhole.

The world had its light stolen by. In the center of the city is Megalo Tower, a building that provides artificial light to replace the light Necrozma had taken previously and to act as a prison to keep it from escaping to other worlds.

It is the home of the Ultra Recon Squad. The Ultra Beasts and its evolution  originate from the world in which the city is located, and are stated to not only be numerous in population, but also popular enough to be treated as starter Pokémon for its residents.

Demographic
The people of this world have pale, gray-blue skin due to the lack of natural light in the world after Necrozma stole all of it. The Ultra Recon Squad wear futuristic suits that allow them to travel through Ultra Space. While other people do exist in this world, they are not encountered in-game, merely referenced inside buildings either hiding from Necrozma after it is broken free from captivity or cheering in celebration after it is defeated by the player.

Trivia

 * As Ultra Megalopolis is part of Ultra Space, if any, or  is evolved here, it would instead evolve into ,  or 's original Kantonian form instead of their Alolan form.

Name origin
Ultrametropolis Ultrópolis Ultra-Mégalopole Ultramegalopoli ウルトラメガロポリス 究極大都會