When I used the Soak method on Landorus in order to paralyze it using Thunder Wave from my Thunderus (which was ko'd by a Rock Slide), Landorus then used Sandstorm but took no damage. I thought this odd until i realized that the Sand Power ability is probably one of those wether abilities that give immunity to weather effect like how Cacturne and Herdier avoid Sandstorm damage and Castform in Hail avoids getting two black eyes
I'm not sure what u're trying to say..Landorus doesn't take sand storm damage bcoz it is part ground type .And sand force increases the the power of rock/ground/steel moves..It doesn't prevent weather damage