Flareon does learn Fire Fang.
Jolteon does learn Thunder Fang (and it had some frames with fangs showed on differents medias).
Glaceon does learn Ice Fang.
Umbreon does have fangs on some frames and stuff on different media.
Dunno about Vaporeon, Leafeon, and Espeon, nothing showed fang of them before, but I doubt they doesn't have fangs, as the other does, it's just we doesnt have Water, Grass, and Psychic Fang.
I love Caterpie, he's a so adorable little bug! ♥ (Also, sorry for my English, I'm still learning it and I'm not a native speaker).