During Season 1, Jeremie and Aelita tried to materialize Aelita, and in Code: Earth, they finally succeeded in doing so. This was achieved in various stages with the Code: Earth Program.

In what episode does Aelita get materialized?

Code: Earth is the twenty-fifth episode of Season 1 of Code Lyoko.

Does Aelita ever get materialized?

She is a human girl who was virtualized onto Lyoko by her father Franz Hopper, before being awoken and befriended years later by Jeremie and the rest of the group. Aelita was eventually re-materialized onto Earth, where she became a student at Kadic Academy with the rest of her friends.