All effects in Gen 5 are in Gen 6.
So this means all Rock-types's Special Defense is raised by 50% in Gen 6.
Here is a list of all effects of sandstorm in Gen 6:
All non-Rock, Ground or Steel type Pokémon are damaged each turn.
Rock type Pokémon's Special Defense is increased by 50%.
Solar Beam power is reduced.
Synthesis. Morning Sun & Moonlight recover 25% of user's HP.
Pokémon with the Sand Veil Ability have their evasion boosted by 20%. Outside battle in 111 & 228, if head of the party, the wild encounter rate is decreased by 50%.
Pokémon with the Sand Rush Ability have their Speed doubled.
Pokémon with the Sand Force Ability have their Ground, Steel & Rock move strength increased by one stage.
The Weather Ball attack's Power doubles and becomes Rock-type .
Hope this helps.