Name: Gerda Hopper, Karmi's fake cousin. (Aelita's long lost little sister )

- Franz Hopper created her for being Aelita's Sister and she was guardian of the core of Lyoko. She's connected to it and she can control it. Her body is actually made from synthetic copy robot which created a version of Aelita. (it's like robot infused with a polymorphic specter) 

Age: 11  (She appeared in Season 4)

- Aelita is technically the oldest one in the group, (chronologically) being 22 years old at the start of the series, but due to her stay in Lyoko, she has biologically remained the age of 12 for the last 10 years. Therefore, Gerda was born the moment Franz Hopper made her. After they left Lyoko, Gerda was left behind after activating the return to the past and the supercomputer was shut down which put her into suspended animation for 10 years, remaining the same age before she met Karmi who found her in the heritage 3 years ago. Due to the supercomputer shut down, her memories were locked away which was given her amnesia.

Personality: Shy at times, gently, sweet, motherly, intelligent, serious at times, always trying to make people smile, protective of her friends, willing to give her life up for her friends, playful. Though she has this strange sickness known as "standstill", which is a coma-like state that occurs during a time of extreme emotional distress or must have been the glitch or virus on her head due to her early awakening or connection to Lyoko. After discovering the truth, She became protective of Aelita like a sister and determine to do whatever it takes to help her.

Looks: Her eyes were blue and had the same hair color as Aelita except in a ponytail.

Clothes: 

On Earth - Wears a blue short dress with white underskirt and red flat shoes. She had a red diamond pendant around her neck. Wears a blue-gray ribbon ponytail on her hair.

On Lyoko - Wears a black spandex suit with blue, yellow and white armor with cyber gear designs. She had the symbol of lyoko embedded on her chest and her appearance is an elf with a 2 diamond mark on her face. Even her ponytail still remained without a ribbon

Hobbies: reading, likes playing guitar and singing, good at hacking, inventing gadgets, jeet kune do.

Powers:

Mental Projection - project objects or any weapons from her mind.  (Mixture of Megaman's battle chip and Void gear from Guilty Crown)

Upgrading - upgrade properties and abilities by touch or sending an energy sphere onto them. It work on herself or her teammates.

Glitch - Phase through any obstacles

Weapon: 

Any weapon she can create

However, her defense program will temporary initiated whenever she was made to protect Aelita from Xana. Her eyes changed and was switched to Auto Mode. It is only temporary once the threat are defeated which reverted back to normal. She was infused with the Core which made her the guardian of Lyoko.

Name: Karmi Nishizawa, the richest japanese girl.

Age: 12 (She appeared in Season 4)

Personality: joker, goofy, silly, always trying to make people laugh, protective of Gerda when it comes to bullying. Though, she develop a secret crush on Odd, even he tried to date other girls which amused her. She's also a hero fan obsession and likes weird cute things.  Also, she got away with it from not being punished or confiscating her phone with a help from her father. Thus, not even Sissy or Principal Delmas can't do about it.

Looks: Has dark red eyes and orange short hair with red headband.

Clothes: 

On Earth - She wears a sailor uniform with green trims along with green socks and gray flat shoes

On Lyoko - Wears black and gray spandex suit with red corset top, red cuffs on the wrist and short along with net long socks with red boots. She had a bat wings on her head and back along with a tail, resembling a succubus. She had a waist holsters that holds 2 weapon.

Hobbies: painting, Jeet june do, plays electric piano or keytar, good at roller skates.

Powers:

Nightmare wings - shoots or blinded hundred of bats at their enemy.

Aqua Velvie - Can pass through any object like its water. She is able to "swim" through solid objects. During this process, objects will pass through her, and she won't be affected. It allows her to move between substances or invalidate attacks from any materials. But it only last for 15 minutes.

Weapon:

Chakram gun (A/N Like Vernal's weapon) - capable of firing energy bolt and thrusting them like a boomerang which she can control them mentally. They were powerful enough to slice through any obstacles or monsters.