Torterra made its first appearance in Top-Down Training! where it was used in a battle against Cynthia's Garchomp. Despite having many powerful attacks such as Giga Drain and Frenzy Plant, it was defeated easily.
It also appeared in Smells Like Team Spirit! where it was used in the semi-finals of the Hearthome City Tag Battle Competition. It was paired off with Ash's Staravia and was up against Brock's Croagunk and Holly's Farfetch'd. It defeated both its opponents single-handedly.
Torterra appeared again in Aiding the Enemy! where it saw the battle between Ash's Turtwig and Paul's Honchkrow. It also witnessed the evolution of Turtwig and its loss of speed. While Grotle was training to become faster, Torterra came forwards on its own to show it that a Pokémon could still be powerful by coping with its lack of speed with strong defense. To prove this, it battled against Ash's Gliscor in a practice match. After teaching this, Torterra returned to Paul's camp. Paul, while curious as to where Torterra had gone, did not push the issue.
In Sliding Into Seventh!, Torterra appeared in a flashback after Grotle defeated Candice's Sneasel.
Torterra appeared as a Turtwig in a flashback in A Pyramiding Rage! watching Reggie's battle against Brandon at the Battle Pyramid.
It appeared again during Ash and Paul's full battle in Pedal to the Mettle!. It fought against Ash's Gliscor and Ash's Staraptor before being recalled. In Evolving Strategies!, it fought against Ash's Chimchar, where it was shown to control its Stone Edge at will to mow down its faster opponents. It then defeated Gliscor before being recalled when Ash's Pikachu was sent out.
It appeared again in a flashback in Uncrushing Defeat! when Ash was remembering it battling Gliscor. He later had another flashback of this at the end of Challenging a Towering Figure!.
It appeared again in DP188 at Reggie's house, along with Paul's Weavile, Ursaring and Honchkrow, they were all unhappy to find out Paul had lost. Although, Torterra does not appear as upset as the others, only giving a sigh.
From what's been seen of its personality, it appears to be calmer and kinder than Paul or his other Pokémon, as it actually went out of its way, and likely against Paul's wishes, to help Ash's Grotle improve its fighting skill.