After you have caught your Pokémon, the first step is to lock in the Nature . Nature breeding has never been easier than now, so this is the quickest, most painless step of the whole process!
The inheritance rules using an Everstone are simple.
Whichever parent holds the Everstone has a 100% chance of passing down its nature. If both parents hold Everstone, it is a 50/50 split between the two natures (not recommended ever, really). Ditto holding an Everstone can pass down its nature too, so if you couldn’t catch the Pokémon with the right nature, just add in the extra step of pairing it with Ditto holding Everstone.
Easy, right? Just remember that after you have picked the nature, one parent must always hold Everstone as you continue to select Ability, Egg Moves, and IVs. It will be really frustrating to have a Pokémon with all the perfect IVs, only to have a random wacko nature because you forgot to keep the Everstone attached to somebody.