Asking because I don't think the location has been updated yet and I love mudkip and want one ASAP
As of now, the only way to capture Torchic, Treecko, and Mudkip is to run into some variation of their evolutionary line while participating in a Dynamax Adventure. It appears that most players will encounter the middle evolutions, Combusken, Grovyle, and Marshtomp in their dungeon runs. You can also find the fully evolved starters, Blaziken, Sceptile, and Swampert available as Rental Pokémon when you first set out on a Dynamax Adventure.
As of now, the only way to capture Torchic, Treecko, and Mudkip is to run into some variation of their evolutionary line while participating in a Dynamax Adventure. It appears that most players will encounter the middle evolutions, Combusken, Grovyle, and Marshtomp in their dungeon runs.
You can also find the fully evolved starters, Blaziken, Sceptile, and Swampert available as Rental Pokémon when you first set out on a Dynamax Adventure.
Source
Hope I helped!