Sword of Justice, Spiritomb
You can choose any Pokémon from the above.
First, find him. Take note of his location.
As first Pokémon in your team I recommend a level 100 one, to make sure you can run away safely from the opponent.
Take one step forward in order to start the encounter.
Beat him or run away, your choice.
Take two further steps forward, in order to position yourself exactly where the pokemon resided.
Enter the X menu and Save your game.
Exit the X Menu and start the EncounterBot.
First, download the Sys-EncounterBot: https://github.com/Manu098vm/Sys-EncounterBot.NET/releases.
Go in the Hub tab and selecet SwordsJustice or Spiritomb under SWSH_Encounter.
Scroll to ConsoleLanguage under FeatureToggle and set it to your language.
Scroll to StopConditions and set them according to what you're looking for.
Go back to the Bots tab, select SWSH_EncounterBot, click Add then Start All.
Alternatively to the previous setup, you can also use the OverworldScan Bot to read the overworld data for the encounters.