I believe there are only two type triangles that would work exactly the same way as the traditional grass-fire-water. Those would be grass-poison-ground and rock-fighting-flying; there's a "super effective" advantage in one direction and a "not very effective" disadvantage in the other. They'd probably work, though I'd probably find it kinda jarring to leave behind the traditional triangle. I'm usually open to change though, so I might be fine after getting used to it a bit. ^-^ As for how it would affect the game, I'm not really sure. I guess a rock-type would have an advantage because of their resistance to normal attacks that most begin with. So that might be unfair.