FOIL

Aluminum has Dissociative Identity Disorder (DID). T.F. (for Tin Foil, and how this personality is referred to) is Aluminum's more violent and vindictive side. She's cunning and very clever, using Aluminum's innocent looks and demeanor to her advantage, especially in her Team Rocket years. T.F. came about due to the mental and emotional abuse Aluminum got from her mother when she was young. T.F. would take over when Aluminum became too upset and close to seizure.

Foil is a literary term that means a character that has traits which are opposite from one of the main characters, in order to highlight various features of that main character's personality. These features can be physical or emotional.

Tin foil is an alternative to aluminum foil. These two definitions gave me the nickname for Ally's other personality.

Aluminum and T.F. belong to me
Pokemon belongs to Game Freak