Arbok, Growlithe, Arcanine, Flareon, Snubbull, Granbull, Houndour, Houndoom, Donphan, Exploud, Manectric, Hippowdon, Stoutland, Darumaka, Darmanitan learn Fire Fang and can breed with Luxray. Make sure Shinx/Luxio/Luxray is female and the breeding partner is male and knows Fire Fang.