It is easy to get Salamech in the Pokémon and Shield match, but only after losing to Gallar's Master: Tarak.
Understand you understand, it's part of End of the game. Tarak is a fan of his "Charizard", he has left your egg Salamese in his room!
How to get Salamce?
After you become a Galar master, return to Paddington and go to Nabal's house.
Upstairs, on the right, you'll find the Tarak Room. On the ground, Pokéball awaits you. This contains Salameh level 5.
If you have a Pokémon shield, you're probably wondering how to get a Gallic Ponytail and how to evolve it into a Gallop.