Solrock's not horrible, its biggest advantage above other Rock-types is Levitate, and its 95 base attack is pretty decent.
Sun Band
Solrock @ Choice Band
Nature: Adamant (+Atk, -SpA), Jolly (+Spe, - SpA)
Evs: 4 HP / 252 Atk / 252 Spe
~ Stone Edge / Rock Slide
~ Earthquake
~ Zen Headbutt
~ Return / Explosion
It has enough of a movepool to use a Choice Band. Stone Edge hits hard, Rock Slide for accuracy, Earthquake allows you the EdgeQuake combo. Zen Headbutt is another STAB move, and allows a nice flinch chance. The last move is really just filler, Return hits relatively hard, as does Explosion with a Choice Band, despite its changed mechanics. You can go Brave with 0 Speed ivs and use Gyro Ball in the last slot too.
Solrock also can get Baton Pass (Through XD iirc), so that's a plus too.
SunPass
Solrock @ Leftovers
Nature: Impish (+Def, -SpA)
Evs: 252 HP / 252 Def / 4 SpD
~ Baton Pass
~ Rock Polish / Calm Mind
~ Cosmic Power
~ Rock Slide / Will-O-Wisp / Magic Coat
You can either Baton Pass speed boosts or SpA and SpD boosts, while Cosmic Power ensures the recipiant will be able to take hits. Rock Slide prevents you from being Taunt bait, while Will-O-Wisp can severly cripple physical sweepers, while Magic Coat can bounce back Taunt or status.
Finally, Solrock is a great special wall under Sandstorm conditions, and can easily stall out threats.
Solrock @ Leftovers
Nature: Careful (+SpD, -SpA)
Evs: 252 HP / 4 Def / 252 SpD
~ Will-O-Wisp
~ Pain Split / Rest
~ Cosmic Power / Toxic / Sleep Talk
~ Rock Slide / Zen Headbutt / Toxic
Firstly, you need Snadstorm for the SpD boost, but once that's in place, it works very well. Will-O-Wisp cripples physical sweepers, meaning you can take hits from both sides of the spectrum. Pain Split is used for recovery, while Rest can heal you from status ailments, though you're a sitting duck for two turns. Cosmic Power is a great addition to this set, and once it gets a few boosts, nothing can OHKO Solrock. Toxic can help wither away walls, while Sleep Talk is there if using Rest. The last move is your attack, Rock Slide hits Fire-types who are immune to to Will-O-Wisp, while Zen Headbutt can flinch slower threats.