Watts is a new currency in Pokémon Sword and Shield. You can use it to purchase useful items from Watt Vendors, who are in the Wild Area. You can speak to them to buy a variety of items, such as TMs, useful Poké Balls, wishing pieces, and there other vendors throughout the Wild Area willing to do tasks for you for Watts.
Farming Watts takes a bit of time, but you have a variety of choices available to you during the middle and later portion of the game. Players are always going to receive 50 Watts when they approach a glowing red den, but it won’t have an ample red light shooting out of the middle. This missing light means the den does not have a Dynamax Pokémon resting within it.
However, the red dens with the glowing red light shooting out of them do have a Dynamax Pokémon, and engaging with it rewards you with 300 Watts. These are not on a timer, and there is not a limited amount of them. You can farm Dynamax Pokémon dens, but they take time because you have to battle.
When you clear out all of the available dens, five or six more pop-up, letting you start over. Of all the choices, this route is likely the quickest because of how fast you can move around the map on your Rotom Bicycle.
When you get your Rotom Bicycle, you gain access to the Rotom Rally. It’s a bicycle ride you have to go through the Wild Area, going to one Watts Vendor to another. You can speak to any of the Watts Vendor in a black-and-white uniform to start one, and you have the choice of picking how far you want to go. The Rotom Rally has you follow a direct path to the other Watts Vendor, and you can’t use your boost.
Instead, you need to smash your bicycle through floating balloons that provide the boost for you, and when you hit the larger ones, it increases your time. You want to reach the other Watts Vendor with the maximum time left. When you finish, you receive a set number of Watts based on your performance. The longer the Rotom Rally, the more Watts you earn.
You can also earn Watts by defeating or capturing Pokémon with a glowing orange aura around them. They randomly spawn throughout the Wild Area, and they’re significantly stronger than other Pokémon of the same species. Trainers would rather catch them because the aura indicates these Pokémon have at least three perfect Individual Values (IVs) on their stats and are extremely useful in creating a Pokemon with six perfect IVs.
You want to visit the Watts Vendor every day you’re on because they have new items available in their inventory.