Pikachu

Biology
Pikachu has a small body with yellow fur as stated in.

Behaviour
Pikachu is known to be troublesome for trainers. Because it is a challenging Pokémon to train, only skilled Trainers attempt to catch one. They usually don't obey their trainers, and try to be independent as their nature requires. But if it lets their trainer command it, the Pokémon can be useful for big battles.

Habitat
No Pikachu has been found or encountered as a wild Pokémon in the nature.

Greta's Foudre

 * Main Article: Foudre (Greta Parker)

Foudre used to belong Diana, who failed her as a Trainer, and ever since, Foudre had been a depressed Pokémon. One day, Diana met and offered her to stick with Foudre for a while until Foudre feels herself better. As Greta and Foudre both agreed on it, Foudre began to travel with Greta and the others.

Light's Pikachu

 * Main Article: Pikachu (Light Yellow)

After started to live at Oak's Laboratory, she became friends with Pikachu. After a long while of spending time together, Oak decided Light to have Pikachu as her travelling Pokémon for safety when she set off a journey across Kanto.

Minor Appearances

 * A Pikachu appeared in Oak's Laboratory. Although he would not respond to anyone, became his first friend.