Pokémon Sword and Shield: How do you get all three starters?

Unfortunately, you can only get one starter Pokémon natively in Pokémon Sword or Shield, and that's the starter Pokémon you choose at the beginning when Leon offers them to you. The other two cannot be caught in the wild, found in Max Raids, accepted as gift Pokémon, or obtained in a normal playthrough. You'll have to trade with others to complete your PokéDex.

It's possible to get starter Pokémon and their evolutions from surprise trades, but you'll have to get lucky. Surprise Trades are just that, a surprise! You'll send one of your Pokémon out and in return, get a Pokémon from another random person. That Pokémon could be anything from a Magikarp to an Intelleon, and you have no control over it.

If you don't have any friends to trade with, this is probably the only way you'll be able to get the starters. The good news is that Surprise Trades happen in the background while you're playing the game. It's easy just to set up a trade and then keep on doing what you're doing until a successful trade happens. Keep at it for long enough, and you'll likely get lucky and obtain more Pokémon for your PokeDex, including the starters. And if you get one of the evolutions of the three starters, you can breed them with another Pokémon in their Egg Group (if they're a female) or a Ditto (if they're a male) to get their base forms.

Trading with friends is a bit more complicated in Pokémon Sword and Shield than it has been in past games.

1. To trade, you'll need to open the connectivity options menu with Y.
2. Choose Link Trade -> Set Link Code.
3. You and your friend must communicate outside of the game to set the same four-digit Link Code, which will then prompt the game to initiate a trade.

From there, your friend can trade you anything they want for anything you want, so you can communicate with friends who have other starter Pokémon and try to obtain them for your PokeDex.

In cases like these, it's a good idea to have you or your friend breed your starter Pokémon either with another Pokémon in their Egg Group (if they're a female) or a Ditto (if they're a male) to get eggs with the base forms of your respective starters, then trade those. That way, you're not giving away your precious partner who got you through most of the game.