>>15267778If you breed a Pokemon with 31/xx/31/xx/31/xx and another Pokemon with xx/31/xx/31/xx/31, you'll get a baby with mix and match, but it will take an eternity for everything to be 31.
You need to find another parent with the same Iv's as it and breed the babies, and pick the best ones to breed with each other.
Here, have a look at this spreadsheet. Study it thoroughly. It may look confusing, but just really pay attention to it.