There are currently a total of 2 Pokémon in the Sandshrew (Alola Form) family. Sandslash (Alola Form) evolves from Sandshrew (Alola Form) which costs 50 Candy.
There is a very low chance that you can get a shiny Sandslash - Alola Form, which has the following appearance:
About
"Sandslash's body is covered by tough spikes, which are hardened sections of its hide. Once a year, the old spikes fall out, to be replaced with new spikes that grow out from beneath the old ones."