Lemme see Fire/Poison has Ground 4x weakness and 2x for the following types Psychic, Water, Rock moves and 3 of them are common moves in the competitive scene. But it has Bug (Double), Fairy (Double), Fire, Grass (Double), Ice, Steel, Fighting resistances in exchange! ;) {XD}
I'm aware you are a Fire-type lover while not much of a Fairy-type fan. Would you like to see a Fire/Fairy Pokémon? Perhaps as a legend or even a starter?