Mr. Mime might be a terrifying amalgam of man and Pokémon, but you will still want to get him to fill out your Pokédex. While Galarian Mr. Mine is in the wild in Sword and Shield, you can only acquire the Kantonian Mr. Mime by trading with an NPC.
Kantonian Mr. Mime won’t stand out in a battle, but if you want to get your hands on every Pokémon, and variant, in the game, then you will want to know how to add him to your collection.
The first thing you will need is Obstagoon. To get an Obstagoon, head to Route 2, then use your Rotom bike with the Surf upgrade to travel across the water. You can regularly find an Obstagoon in the grass in that area.
Once you get your Obstagoon, head for Spikemuth. Fly to Route 9, then cycle to the Challenge Gym in the center of the town. You will find a Team Yell grunt sitting at a booth in the left corner. Speak to him, and he will offer you a Mr. Mime if you give him Obstagoon. Just accept the trade to get your Kantoniam, Mr. Mime.
This method is the only Kantonian Mr. Mime available in the game; you cannot breed it with other Pokémon to get more, as any Mr. Mimes that spawn from the eggs will be the Galarian version.
Now that you have added Kantonian Mr. Mime to your Pokémon collection, you are one step closer to catching them all.