The problem with Torterra is its 4x weakness to Ice, which every pokemon seems to be packing these days. It can take a physical hit or two, but it's not nearly fast enough to heal and set itself up with Curse or Swords Dance, all while avoiding death. This is the chief reason it's in UU. And besides this, it's movepool is incredibly limited, basically making sure the only powerful moves it has are STAB, which doesn't bode well for taking out Dragons, Fliers, and the like. However, no one can argue that you don't innovate, which the metagame is in desperate need of. As such, I'll present this:
Torterra@ Life Orb
Ability: Overgrow
EVs: 252 Sp. Def/ 152 HP/ 60 Atk/ 40 Def
Impish Nature (+Def, -Sp. Atk)
-Earthquake
-Wood Hammer
-Synthesis
-Curse/ Swords Dance
Basically a copy of my Hippowdon set, all you need is a turn of set-up and you're ready to sweep. Curse or Swords Dance is a matter of personal preference. I personally strongly prefer Curse over Swords Dance, as Curse will mean you can spend more time attacking and less time healing. Or, if you want a pure wall, try this set:
Torterra@ Leftovers
Ability: Overgrow
EVs: 252 Def/ 200 Sp. Def/ 52 Atk
Adamant Nature (+Atk, -Sp. Atk)
-Amnesia
-Synthesis
-Stealth Rock
-Seed Bomb
Seed Bomb Wood Hammer, because the last thing you want something as frail as this to do is deal itself damage. With just one Amnesia you can withstand any Ice attack, giving you time enough to heal and dish some damage before healing. Stealth Rock deals damage to Fliers. Not the best set, but Torterra isn't the best pokemon.