Krokorok made its first appearance in A Sandile Gusher of Change! as a Sandile, where it was revealed to be the leader of a group of Sandile who lived near a local spa resort. It and the group caused trouble at the spa resort on Route 1 so that they could get the attention of the owners. It was actually trying to save the other Pokémon in the area because it knew that a geyser would soon erupt. With the help of Ash, Iris, and the son of the spa resort owner, Dan, Sandile was able to save the Pokémon. In the end, Sandile was shown to have gained respect for Ash, and as such, began to follow him.
Sandile appeared again in Here Comes the Trubbish Squad!, where it wanted to battle Pikachu. It randomly attacked with Stone Edge, not caring that there were small children close by. It was sent blasting off by a wild Trubbish's Sludge Bomb and Pikachu's Iron Tail.
Sandile reappeared in Dancing With the Ducklett Trio!, separating Ash from the group in order to battle Pikachu again. However, a wild Ducklett stole its sunglasses and stopped the battle. Sandile was deeply saddened without its sunglasses, losing its usual confidence and becoming quite cowardly. With Ash and Pikachu's help, it defeated the Ducklett and claimed its sunglasses back. Later, after being healed at the Pokémon Center, Sandile finally got the battle it wanted with Pikachu. Sandile dominated the battle to start with and eventually evolved into Krokorok. Pikachu soon gained the upper hand however, and sent Krokorok blasting off when his Electro Ball attack collided with Krokorok's Stone Edge attack, causing the stones to hit Krokorok and send it flying.
After a long absence, Krokorok returned at the end of BW064 with the same goal of defeating Pikachu in battle. In the following episode, it battled against Pikachu, and ended up causing the two of them to go flying. It was later found by Ash, and helped them locate Pikachu. It was revealed that Krokorok had followed them through various locations, including Nimbasa City, in order to have a rematch with Pikachu. It also followed them through Chargestone Cave, wherein it was the actually that caused a pen to be stuck in the Klinklang in BW063. Krokorok later allowed Ash to use it to help Nick learn to battle, and it eventually teamed up with Pikachu under Nick in a Double Battle. Throughout the battles it participated in in the episode, it was shown that it still lost its confidence when without its sunglasses, having to result to finding them before going back in the battle. After the Double Battle, it started to leave until Ash invited it to join their team. Krokorok happily agreed, and was caught by Ash in a Poké Ball.
As a Sandile, Krokorok was shown to have a very caring side, trying to save a group of wild Pokémon after sensing an imminent geyser eruption in A Sandile Gusher of Change!. It's also extremely competitive, confident and proud of its abilities, even to go so far as to follow Ash throughout his entire journey, up until BW065, wanting to battle against Pikachu. However, it was revealed in Dancing With the Ducklett Trio that whenever it would lose its trademark sunglasses, it would immediately become timid and begin to cry until it got them back.
