You can get a Rockruff with Fire Fang as an egg move with the following pokemon: Arbok, Growlithe, Arcanine, Rhyhorn, Flareon, Snubbull, Granbull, Houndour, Houndoom, Donphan, Poochyena, Mightyena, Exploud, Mawile, Electrike, Manectric, Shinx, Hippowdon, Lillipup, Stoutland, Sandile, Darumaka, Darmanitan, Litleo, Pyroar, Litten, Torracat, Incineroar, Yungoos, Lycanroc-Midnight. But you won't get an Own Tempo by breeding it.