How to Get and Use Gold Bottle Caps in Pokémon Sword and Shield
Bottle caps are a useful currency in Pokémon Sword and Shield because they allow you to Hyper Train any of your level 100 Pokémon. You can find them from several methods, such as buying them from a Battle Point (BP) vendor at the Battle Tower, seeing them after beating Max Level Raids, through the Digging Duo, and competitive Ranked Matches. Sometimes, you might be lucky and discover a gold bottle cap.
Gold bottle caps are different from traditional bottle caps because you can use them with the Hyper Trainer to maximize all of the Individual Values (IVs) of a Pokémon, rather than a single one. You need to have a level 100 Pokémon to do this, though. The Hyper Trainer is in the Battle Tower, on the right side. Speak to them if you have a regular or gold bottle cap to make your Pokémon that much stronger.
Getting gold bottle caps is no easy task, though. You'll find yourself hard-pressed to locate them. You can find them through the conventional means of regular bottle caps, but you have the odds stacked against you.
You cannot purchase them from the BP Vendor at the Battle Tower. You need to reach a high enough rank in the Battle Tower challenge to receive one for a reward, and it's a top-ranking, so you'll need to do plenty of practice before you find a gold bottle cap in your inventory.
The other method is through the Digging Duo, located in the Bridge Field area of the Wild Area, nearby the Pokémon nursery. Speak to either of the brothers to spend 500 Watts to have them start digging. They'll dig up treasures, and you'll receive numerous different rewards. The bottle caps are rare, so the chances of finding a gold bottle cap through this method are meager.
You might have a chance of locating a gold bottle cap from the Pokémon Max Level raids, but you will likely only see them through the five-star choices. If you get can get a responsible party of players to assist you, these five-star raids should prove no issue.
Reliably, you'll want to go through the Battle Tower challenge to see how far you get. The higher you go, the more chances you have adding gold bottle caps to your inventory.