I want to make sure I get a Modest Mewtwo, and want a way to make sure it’s IVs are high in speed and special Atk.
Is LGPE also doing the same as Gen 6 and 7 with the 3 IVs guaranteed thing on Mewtwo, even tho it’s a Kanto remake?
Yes, Mewtwo does come with three perfect IVs.
There is a judge feature that you can unlock by registering 30 unique species in your Pokédex and talking to one of Professor Oak’s aides at the easternmost part of Route 11 in a building that separates it from Route 12. You will then be able to check IVs in the summary screen.
You can guarantee natures of Pokémon you encounter for the rest of the day by talking to a lady in Celadon City. For modest in particular, tell her that you would like to water blue flowers and trim red flowers. Keep in mind that this will cost you 10,000 pokedollars.