It’s a lot of work but this is the only way you’ll be able to catch a Shiny Meloetta, and Pokémon has hinted it may do something similar for other complete Pokédexes in the future.
For example, if you have a shiny Kyogre as your buddy, you’ll see a shiny Kyogre pop up on the overworld map. Once you tap it and catch the mimicking Pokémon, after it’s in the ball ...