Rotan Power Plant

The Rotan Power Plant is a power plant in Elecspress City, which uses a nuclear generator to power the Rota region. All Pokémon in it are Electric-type, except Nucleon and Meltan. Eevee can also be evolved into Nucleon here, and the Power Plant has a special magnetic field (evolving Magneton, Nosepass, and Charjabug into Magnezone, Probopass, and Vikavolt respectively). Hordes of Meltan can be encountered here. To do so, put a Steel-type Pokémon at the head of your party. This gives you a 5% chance of finding five Meltan (independent of the other encounter rates, Meltan overrides whatever Pokémon would otherwise be encountered, as its check comes before the normal one). The explanation for this is that Meltan are attracted to metals. This is also the only way to get a Horde Encounter in any Generation Ω game. Also, unlike previous Horde Encounters, throwing a single Poké Ball at these Meltan attempts to catch them all, using the capture chance that benefits the player most out of the five Meltan. In addition, to evolve Meltan into Melmetal, the player must splice ten Meltan using the DNA Splicers. (Note that the battle mechanics remain the same in the Minus World; this is one of the few scenarios where you send out a single Pokémon).