Well, I'll list some pokes who have higher(or decent) Special Attack then Attack for rock types.
- Magcargo
- Tyrannitar
- Lunatone
- Cradily
- Probopass
- Omastar
Now let's eliminate some who function better as walls, or who simply aren't great.
Elimination list:
- Probopass
Gosh that was short.
So for Magcargo to start.
Absolutely horrendous Speed which almost completely eliminates it as any sort of sweeper unless in TR. It's Defense is much better then any other stat so I would personally use it as a Defensive wall. Let's move on to some better candidates.
Lunatone.
This guys highest stat is his SAtk. Base 70 speed isn't all that great though, and frankly 95 base SAtk is only just viable. However he can still be used although he is definitely outclassed.
Lunatone @ Choice Scarf
Trait: Levitate
EVs: 252 SAtk / 252 Spd / 4 HP
Timid Nature
- Psychic
- Shadow Ball
- Icy Wind
- Hidden Power [Fighting]
This Set provides limitless coverage. You can use Scarf and nature to make up for the low speed but there is another possibility.
Lunatone @ Leftovers
Trait: Levitate
EVs: 252 SAtk / 252 Spd / 4 HP
Modest Nature
- Rock Polish
- Shadow Ball
- Psychic
- Hidden Power [Fighting]
So this set again makes up for low speed whilst giving you the coverage in those three moves. It's ok, I wouldn't use it outside of it's tier but it can work.
Cradily
This poke has several roles it can fill and one of them is Special Attacker with bulk. Access to Storm Drain means you can predict and get a boost to your SAtk. Let's look at some sets.
Cradily @ Leftovers
Trait: Storm Drain
EVs: 252 SAtk / 252 HP / 4 Def
Modest Nature
- Giga Drain
- Earth Power
- Hidden Power [Ice]
- Toxic/Ancient Power/Filler
Last moveslot is fairly optional. Bulky Offense, this poke is really nice and can, as I mentioned, fill many roles. You could also run Specs, but I like Cradily as a Bulky sweeper with options so you aren't switching so much.
Tyranitar
I would say this guy has the widest possible movesets available. With access to so many Special attacks he can run some pretty boss sets.
Tyranitar @ Choice Specs
Trait: Sand Stream
EVs: 252 SAtk / 252 Spd / 4 HP
Modest Nature (Timid for speed of wanted)
- Fire Blast
- Ice Beam
- Dark Pulse
- Thunderbolt/Focus Blast/ HP [Something]
Fairly standard everything.
Tyranitar @ Choice Scarf
Trait: Sand Stream
EVs: 104 Atk / 252 HP / 152 SAtk
Naive Nature
- Fire Blast
- Ice Beam
- Stone Edge
- Crunch/Pursuit
Mixed Scarf TTar set. Wrecks absolute havoc.
Most support TTar's will run Pursuit but you can go for standard support with a Special Move.
Tyranitar @ Life Orb
Trait: Sand Stream
EVs: 252 HP / 252 SAtk / 4 Spd
Timid Nature
- Fire Blast
- Stealth Rocks
- Ice Beam
- Focus Blast
Life Orb set with SRocks. Set is decent but walled by Starmie, Jellicent, and Tentacruel in OU and Slowbro from UU.
Omastar
Can't believe I forgot the Star of Omaha
Beautiful 115 SAtk and access to Shell Smash, gg
Omastar @ Focus Sash/White Herb
Trait: Shell Armor/Swift Swim
EVs: 252 Spd / 252 SAtk / 4 Def
Modest Nature
- Shell Smash
- Hydro Pump/Surf
- Ice Beam
- Hidden Power [Grass]/Hidden Power [Fighting]
Star of Omaha, buh bye, cya later, adios. Try to Smash on the switch to avoid priority aboose.
♪$tarPower♪
seconds ago: You forgot the pie
Master Kijani
seconds ago: phew
Master Kijani
seconds ago: ok good
Hoιγ Σiκe*
a minute ago: Nothing..
Master Kijani
a minute ago: what did I forget?
THE PIE
So those are a few sets and a few pokes you can try. There are others that are mentioned in the other answers such as Arceus in Ubers, and Archeops.
