As the title says, Hisuian Growlithe simply does not pass down the Hisuian form in breeding, and only produces Kantonian Growlithe offspring, including when an everstone is used to preserve the form in breeding. Tried breeding it with another Growlithe, with Ditto, using a female Growlithe, a male Growlithe, with everstone, and without everstone. Every time it had resulted in a Kantonian Growlithe.
Here's a clip of me attempting this, if it's any help. I'll try to provide any further information if it's needed, thanks for your time.https://medal.tv/games/minecraft/clips/fpAARuVQ7eJm9/d1337dsqGPcJ?invite=cr-MSxIZWUsNTMwMDA1NzIs