IV breeding requires the Destiny Knot item. This guide will help you get a Destiny Knot in Pokemon Sword and Pokemon Shield so you can start IV breeding Pokemon and building your competitive teams.
There are two methods to obtain the Destiny Knot item in the games.
Open the town map and use the flying taxi to travel to Hammerlocke. Go inside of the Pokemon Center and at the right you will see a female staff member. She will sell you a Destiny Knot for 10 BP.
To earn BP (Battle Points), you must unlock the Battle Tower after finishing the game.
Get a Pokemon level 21 or higher with the pickup ability. The higher the level, the better. Higher-level Pokemon obtain better items even though getting a Destiny Knot via pickup is very rare. Therefore the time spent will not be an absolute waste if you do not get the Destiny Knot.
List of Pokemon with the pickup ability in Pokemon Sword and Shield:
The above is a list of Pokemon with the Pickup ability. Zigzagoon, Linoone, Bunnelby, and Meowth are all common Pokemon found in the Wild Area.