You have two solutions to this problem.
1)Use a strong Dark or Steel type (e.g. Tyranitar,Metagross),and teach it Toxic and Sandstorm (obviously Tyranitar won't need Sandstorm).Toxic the Sableye and It'll be dead in no time.
2)A better solution for this,i'd say,is get a Pokemon with Mold Breaker - Haxorus and Rampardos are good choices.Mold Breaker cancels out the wonder guard an allows you to him Sableye freely.(I'd say this is better because, in my opinion at least,I'd rather give my Tyranitar moves like Stone Edge and Earthquake,but i'm by no means any professional battler.)
These 2 solutions should easily help you destroy wonder guard Sableyes and Spiritombs.