Pokémon X and Pokémon Y

Psychic > Fighting > Dark > Psychic?

I think the reasoning some people have against that "triangle" is that psychic can't do actual damage to a dark type pokemon, whereas fire types can still do damage against water types (even if it's minuscule). The only other ones that follow this manner would be Rock/Fighting/Flying, Fire/Rock/Steel and Grass/Poison/Ground, which wouldn't be too bad.