Sandstorm is like Sunshine and Heavy Rain, but with an interesting caveat- rather than blanket-boosting or deflating moves, Sandstorm is affected by the type of the pokemon in the battle. Because of this, a Sandstorm team is a bit more restricted than a Heavy Rain or Sunshine team- but its effects make it a considerably stronger boost to its team members in some cases.
As with the other weather changes, Sandstorm has a trigger move (Sandstorm, what a surprise) and lasts 5 turns from that move, doubled if the pokemon is carrying a Smooth Rock. This is sometimes an easier choice and sometimes a hard one- many pokemon that benefit from Sandstorm are defensive and really get a boost out of Leftovers, and others are highly offensive and lose a lot by not carrying an appropriate attacker’s item. Some pokemon, though, will barely notice the discrepancy, particularly things like Gastrodon, which has access to Recover anyways.
During a sandstorm, there are two static effects. First of all, any pokemon that is not Rock, Ground, or Steel-typed and does not have the Sand Veil or Sand Rush ability will take 1/16 of their maximum HP every round. This is a surprisingly powerful crippling effect to any team that is not either prepared to change the weather itself, nor also a sandstorm team. Second of all, Sandstorm boosts the Special Defense of all Rock pokemon by half- a great boon to most Rock types, who tend to have terrible Special Defence and worry about neutral attacks like Psychic or Dark Pulse and sometimes get devastated even by things like Power Stone or Flamethrower that they are resistant to.
As abilities go, the Sandstorm abilities are all quite good. Sand Veil pokemon become more evasive, as though they had a use of Double Team up. Sand Rush pokemon double their speed, just as Swift Swimmers in water. And Sand Force pokemon improve the power of not only their Rock moves, but also their Steel and Ground moves. Castform, curiously, doesn’t change in a Sandstorm.
Sandstorm has a much shorter list of moves it affects, also. Solarbeam gets its power cut, and it minimizes Synthesis, Morning Sun, and Moonlight just as Heavy Rain does. Other than that, it also doubles the power of Weather Ball and makes that move a Rock move.
Sandstorm’s effect on defenses is in many ways far more profound than the move-boosting and -deflating effects of Sunshine or Heavy Rain, making it far easier for a Sandstormer to take advantage of- and much harder for an opponent to turn to their own advantage. A n umber of Rock-types that are usually pure physical walls become a lot more durable, and many tanks and such (hi, Tyranitar) can become downright terrifying. The ancillary boosts are amazing as well. Sand Rush Stoutland nearly becomes a sweeper in a Sandstorm, and actually has the physical attack movepool to pull it off. Sand Veil Cacturne goes from a frail gimmick pokemon with Sucker Punch to a passable sweeper, and can reach for a much higher destructive potential by putting Sand Veil’s evasion together with Brightpowder and Substitute- and then Focus Punch half of everything into oblivion. Sand Rush Excadrill is already doing horrible things to the metagame by being a Steel-typed sweeper that cuts anything in two, and anything with Sand Force is going to be blowing holes in most opponents. Setting such pokemon up with others that both endure Sandstorm and have differing weaknesses and functions (heavy Ground/Water walls like Gastrodon or Swampert; oddball walls like Forretress; devastating fliers like Aerodactyl) can result in a truly terrifying team... until someone makes it rain on you.
