Sand Stream
Summons a sandstorm that lasts indefinitely upon entering battle.
Full effect
The weather changes to a sandstorm when this Pokémon enters battle and does not end unless cancelled by another weather condition. If multiple Pokémon with this ability, Drizzle, Drought, or Snow Warning are sent out at the same time, the abilities will activate in order of Speed, respecting Trick Room. Each ability's weather will cancel the previous weather, and only the weather summoned by the slowest of the Pokémon will stay. Overworld: If the lead Pokémon has this ability, the wild encounter rate is halved in a sandstorm.
In game description
The Pokémon summons a sandstorm when it enters a battle.
Pokemon with Sand Stream
Using Sand Stream in Cobblemon
Abilities are passive and always active, so Sand Stream costs you nothing to run. If it is marked hidden on a species above, expect it to be harder to obtain: servers differ in whether hidden abilities come from breeding, an Ability Patch, or events.
See the Pokedex for which abilities each species can have, and IVs, EVs and breeding for how to actually pass one down.