If you want to buy vitamins to make your Pokémon stronger, or new items for your character, you'll need money.
In Pokémon Sword and Shield, there are several ways to get in-game currency (Poké Dollars). Here are the most efficient ways to do it.
Winning the game
The passage of the game in itself will bring you large sums of money. Fighting trainers and collecting items in Pokémon Sword and Shield is profitable. You can give the Pokémon a Coin Amulet to keep during the playthrough, which will increase the profit. You will also gain access to more areas of the wilderness and increase the amount of watts (the currency of the wilderness) you get there after completing the main story.
Wild land
Once you win the game, Wild Area will be the best place to earn money. There are valuable items throughout the wilderness such as stardust, star shards, mushrooms, and rare bones. There is a Pokémon breeder you can fight that gives you $24,000 Poké for defeating her. You can also trade your Watts with Watt Traders for luxury balls that sell for a great price.
Maximum number of raid battles
By winning Max Raid Battles, you will receive several valuable rewards. You also don't need to catch a Pokémon in a raid to get these rewards; you just need to win the raid. This can bring you valuable items as well as Technical Records (TR) which are sold at high prices in stores.
Tournament
After beating the game, you can challenge the tournament in Wyndon as many times as you want. If you want to get the maximum profit, be sure to invite Hop or Leon, as they give significantly more than other applicants. After you win the tournament, Ball Guy will also give you a random reward. Some of the awards he gives are quite valuable.
Money in Pokémon Sword and Shield is much more valuable than in previous games. This is mainly due to the fact that you can now fully train a Pokémon with vitamins, which are very expensive. There is also a wide selection of beauty products at high prices. Be sure to use all these methods to top up your wallet!