Haki was a mistake. Beating Logias should just require using the opposite element or something they are weak to.

>Smoke: Wind to scatter the smoke
>Fire: Water, magma to smother, cold
>Ice/Snow: High levels of heat
>Magma: Extreme cold
>Sand: Water
>Lightning: Rubber
>Light: Reflective glass
>Swamp: Heat (dries out mud)