Don't use this
Carracosta @ Life Orb
Trait: Solid Rock
EVs: 252 Atk / 4 Def / 252 Spe
Adamant/Jolly Nature
-Shell Smash
-Stone Edge
-Waterfall
-Aqua Jet
Although this set does pack a lot of power, I find due to the prevalence of physical walls that can stop this set, it doesn't always to accomplish a lot. Alomomola, Tangela, and Siesmitoed in particular are common enough to make this set rather unusable. Although he can break through walls (other than Seismitoad) after a boost, I have a different set in mind to make use of Carracosta's decent mixed attacking stats to break through it's checks faster, and decimate Seismitoad which is one of the best counters to the more common Physical set.
Use this instead
Carracosta @ Life Orb
Trait: Solid Rock
EVs: 4 Atk / 252 SpA / 252 Spe
Naive Nature
-Shell Smash
-Stone Edge
-Hydro Pump
-Hidden Power Grass
Although Carracosta is still hard to setup, using this mixed set not only does Carracosta more effectively beat checks and obliterate Seismitoad, he also beats Pokemon that would usually laugh at a Specially-based SS sweeper. I feel that this is not only more usable then the standard set, it also manages to not be completely outclassed by Gorebyss by virtue of a powerful STAB Stone Edge. I also like that although this set uses a Speed boosting Nature, it can pretty much deal just as much damage thanks to Hydro Pump, although the low accuracy may bother some people. I've always liked Carracosta flavour wise, I think this shows that he can still be relevant.
Physical calcs
+2 252+ Atk Life Orb Carracosta Stone Edge vs. 248 HP / 252+ Def Eviolite Tangela: 179-212 (53.75 - 63.66%) -- guaranteed 2HKO
+2 252+ Atk Life Orb Carracosta Waterfall vs. 248 HP / 252+ Def Eviolite Tangela: 70-84 (21.02 - 25.22%) -- possible 4HKO
+2 252+ Atk Life Orb Carracosta Stone Edge vs. 104 HP / 252+ Def Alomomola: 341-402 (68.61 - 80.88%) -- guaranteed 2HKO
+2 252+ Atk Life Orb Carracosta Stone Edge vs. 200 HP / 252+ Def Seismitoad: 175-208 (43.64 - 51.87%) -- guaranteed 3HKO
Mixed Calcs
+2 252 SpA Life Orb Carracosta Hydro Pump vs. 248 HP / 8 SpD Eviolite Tangela: 250-295 (75.07 - 88.58%) -- guaranteed 2HKO
+2 252 SpA Life Orb Carracosta Hidden Power Grass vs. 104 HP / 152 SpD Alomomola: 424-499 (85.31 - 100.4%) -- 6.25% chance to OHKO
+2 252 SpA Life Orb Carracosta Hidden Power Grass vs. 200 HP / 56 SpD Seismitoad: 691-816 (172.31 - 203.49%) -- guaranteed OHKO
+2 4 Atk Life Orb Carracosta Stone Edge vs. 248 HP / 8 Def Eviolite Roselia: 368-434 (121.45 - 143.23%) -- guaranteed OHKO
+2 4 Atk Life Orb Carracosta Stone Edge vs. 248 HP / 0 Def Ludicolo: 402-473 (110.74 - 130.3%) -- guaranteed OHKO