Sand Veil is an Ability that increases the evasion of a Pokémon by 20% in a Sandstorm and grants immunity to the passive damage caused by Sandstorm. So, for example, if a Cacturne (which has Sandstorm as its only possible Ability) would be in such a Sandstorm, it wouldn't be hurt by passive damage thanks to Sand Veil, even though it isn't a Ground, Rock or Steel type Pokémon. Eleven Pokémon have Sand Veil as their Ability.

In the overworld, if the Pokémon with Sand Veil is leading the party in an area with a sandstorm, such as Route 228 in Sinnoh, Sand Veil decreases the wild Pokémon encounter rate by 50%.

Pokémon with Sand Veil

Single ability

Sandshrew	Sandslash	Cacnea	Cacturne	Gible	Gabite	Garchomp
			File:332.gif

Dual ability

Diglett	Dugtrio	Gligar	Gliscor

Arena Trap	Arena Trap	Hyper Cutter	Hyper Cutter

Sand Veil (Ability)

Pokémon with Sand Veil

Single ability

Dual ability