>>33107176In Generation III, "kiba" moves were translated as "Fang." So "Dokudoku no Kiba" (Toxic Fang) became Poison Fang.
Thunder Fang, Fire Fang, and Ice Fang all have "Kiba" in their Japanese names.
"Kaminari no Kiba" (Thunder Fang)
"Honou no Kiba" (Fire Fang)
"Koori no Kiba" (Ice Fang)
Psychic Fangs is a different story, as its Japanese name is "Saiko Fangu" (Psycho Fang). Since it doesn't have "kiba" in its Japanese name, its English name can't have "Fang" in it. So it has "Fangs" instead.