Amanda, as a Snivy, was originally owned by Cedric Juniper, along with a Tepig and Oshawott. Along with a set of similar Pokémon owned by his daughter, Cedric intended to give Amanda to Trainers starting their journeys. However, N broke into the lab in an attempt to liberate the three Pokémon due to his hatred of Pokémon distribution. His attempt was only partially successful, however, as while the Tepig ran away, Amanda decided to go with N, and Oshawott staying with Cedric.
Amanda made her first appearance as a Snivy in Castelia City. She is spotted by Cheren's Snivy, who attempts to get her attention by waving, only for Amanda to ignore his greeting. She is interrupted by N's Zorua, who tells her to get moving as they make their way to Route 4.
Sometime later, Amanda has evolved into a Servine and assists N in knocking White into the Nimbasa Rondez-View Ferris Wheel. N has Amanda tease White's Gigi by having her tie Gigi up and hold her into the air. Having no choice, Gigi attacks the Servine with an Ember, knocking her away and freeing the Fire Pig Pokémon from her grasp. Having seen enough, White attempts to jump out of the Ferris Wheel and gestures Gigi to do the same. Surprisingly, Gigi goes to N's side, shocking White who falls out of the car and onto the ground below.
As N and Gigi watch White from the Ferris Wheel, N sends Amanda to White's aid. After White was rescued by Marshal, Amanda follows Black while he takes her to the hospital. When White wakes up in the hospital, the first thing she sees is Amanda looking from behind the curtain and immediately crawls back under her covers and screams. After White explains her situation, Black angrily tries to get Amanda to tell him where N is only for her to arrogantly ignore him.
When White tries to capture a Deerling to use in the Battle Subway, she angers the Pokémon and it begins to attack her. Much to White's shock, Amanda comes to her aid and blocks the Deerling's attack. Even more surprising to White is that when Black suggests that she commands Amanda to attack the Deerling, she listens to her commands and helps her catch it.
During White's training on the Battle Subway, White used Amanda to battle Ingo's Klinklang. Although White used a strategy to clog Klinklang's gears up with leaves, the battle ends in a tie. When White attempts to give Amanda a nickname, she gets a slap from Amanda's tail in response. During a battle with a group of wild Vullaby, Amanda teams up with Bianca's Oshawott and a Meloetta to help defeat the group's leader.
Sometime before White had finished her training on the Battle Subway, Amanda had evolved into her final form, a Serperior. She was used to battle N near Icirrus City along with Black's Buoh and Cedric's Samurott.