Base Stats at Level 50 (Averages taken from http://bulbapedia.bulbagarden.net/wiki/Torterra#By_leveling_up)
Sp. Attack- 106
Sp. Defense- 116
I have played with my trusty Torterra since Pokemon Diamond first came out. I used a lot of TMs and Heart Scales at the move recall guy to get the best combination of moves. There really are two different types of movesets. One is the kind that is awesome and fits Torterra's looks and nature, and the other is the most practical that will beat a lot of different types. Here they are:
Frenzy Plant - Great damage against Rock, Ground and Water. The standard hyper-attack that starters should have.
Leaf Storm - Torterra's signature move. Be cautious as if you keep using it it will get weaker because your Special Attack will harshly fall every time.
Earthquake - No explanation needed. The best Ground move in all the generations!
Synthesis - Healing powers. Also, this Pokemon has a freaking tree on his back. Why not have some chlorophyll healing powers?
Earthquake - Deals with Electric, Fire, Poison, Rock, and Steel. Also attacks both enemies in a Double Battle
Giga Drain - Deals with Rock, Ground, and Water. Also gives you some health back
Stone Edge - Deals with Bug, Flying and Ice. Also forms the powerful EdgeQuake combo.
Rock Climb - The three moves above basically deal with all types that are strong against Torterra. I put this here because it can be reused (an HM) and has decent damage, utilizing Torterra's powerful Attack stat. This will do around 100 damage against a neutral opponent. Other very useful moves to replace this with are Toxic, Cut, Rock Polish, or Rest. You pick.
These are all great moves you can use. Once again be careful with that Leaf Storm move. I play Pokemon Diamond, a Generation IV game, but I know that some people get Torterras in their Generation V and VI games or whatever. I personally think the games are great up to Generation IV but that's just one person's opinion. The Generation II and III games are the best.
Thanks for reading this answer by Likeawhisper.