Ophie
Salingerian Phony
While I'm indifferent to the idea, I'm not sure if it would completely work since a lot of trainers will try to bring their Galarian Slowpoke to evolve it, while others are adamant of using new teams. They could do a compromise and make it so that you can only do the towers and the new sparring/training thingy using pokémon caught in the Isle of Armor for your first play through.
I think it can still work. I highly doubt that Slowpoke you get at Wedgehurst Station will be the only time you can get Galarian Slowpoke. Rather, I am certain they'll be available in the wild in Isle of Armor, either as overworld encounters or through Max Raid Battles. Galarian Slowbro may be available through Max Raid Battles too, kind of like how you can get Runerigus that way instead of evolving Galarian Yamask.