Sabrina

Sabrina is a former member of the Team Rocket Triad and is the Saffron City Gym Leader who specializes in Psychic Pokemon. She herself is a powerful psychic that first manifested her powers as a child when she managed to bend a spoon with her mind. However the life of a gym leader was not enough for her and she joined Giovanni in his pursuit to use Pokemon to try and take over the world. She is unwaveringly loyal to Team Rocket and is merely biding her time until the day Giovanni returns to lead them once again. 
=History=
See Here
Her history here does not elaborate on her childhood (which is more or less the same as the game canon). To elaborate on this, my headcanon will be establishing certain things about her childhood, taking a few details from other versions of Sabrina.
As a child, Sabrina was a relatively ordinary girl. She was quieter than most and more intelligent than her peers, but much loved by her parents. She was a girl of only five years old when her psychic powers first manifested in the form of bending a spoon that she casually tossed away. From then on her powers only grew in strength. At first her parents were willing to encourage this, but they soon grew wary and eventually fearful of her abilities. She formed a close bond with the Pokemon she acquired, particularly with an Abra (later her current Alakazam) that she gained as a young child. By the time she was eighteen, she was already a powerful Pokemon trainer and was the Gym Leader of Saffron, after she and her followers expelled the Fighting Gym leader. She took her place as one of the eight Gym Leaders, seemingly satisfied with her position. At least until she met Viridian Leader Giovanni, who made her an offer for power she felt compelled to follow.
=Personality=
From a very early age, Sabrina first discovered she possessed psychic abilities, after carelessly bending a spoon when she was still very young. She dedicated her life afterward toward honing her ability, creating the woman she is today. Because of her abilities, she has buried most of her emotions due to the fact that her psychic abilities would be difficult to control otherwise. Thus she attempts to remain humorless and serious at all times to prevent herself from losing control. This is no longer something that requires exceptional effort from her, as she has learned to behave this way since childhood and it now comes perfectly natural to her. But in spite of that cold exterior, she is not entirely emotionally bankrupt. She is not above reveling at her foe's mistakes and failures or expressing shock and anger at her own. Having once been considered nearly unbeatable, she possesses a certain amount of smugness that has been only somewhat tempered by her defeat to Blue and the struggle against Lorelei of the Elite Four.
Sabrina has proven herself in the past to be capable of cruel and sadistic acts. She has shown no hesitation in past attempts to not just defeat, but to attempt to kill trainers and their Pokemon who get in her way. She felt no remorse for the Pokemon experimented on by Team Rocket, readily participating in the capture of a mutated Eevee and in the capture of the Legendary Birds Zapdos, Articuno, and Moltres (the last of which she captured herself). Unlike Lt. Surge and Koga, her efforts seem less motivated by a desire for power, but a sense of loyalty for Giovanni. It's not quite clear what he has done to earn such admiration (though Sabrina is obviously infatuated with him), but her loyalty remained unwavering even when he went missing for two years. However this sense of loyalty remains strong even with temporary allies. She was over to overcome her grudge against Blue when faced with a bigger enemy in the form of the Elite Four, who were intent on wiping out humanity. When she was handcuffed to Blue, she refused to let the young girl come to harm, even at the suggestion of removing the younger girl's arm. Although Sabrina was all too quick to to end their arrangement once Lorelei was defeated, Sabrina was willing to put her life on the line to save her. 
==Strengths==
Physical: Although a trainer, Sabrina has limited combat experience of her own, being well acquainted with dangeorus Pokemon battles that require quick moving even in the midst of a dangerous Pokemon battle. As a result she is physically fit and when her arm was bound to Blue's, she was able to carry the unconscious thirteen year old girl under her arm while still commanding her Pokemon. She is also a power psychic with her most prominent talent being telikinesis. Although she doesn't measure up to the power of Pokemon, she is able to bend objects with her mind, lift objects, and provide her own levitation. She can teleport too. Her abilities also allows her a 'mind's eye' that gives her the ability to see things with her mind, allowing her the ability to see through smokescreens or dark areas with no difficulty. It also allows her to perceive things invisible to human eyes, such as psychic barriers. 
Mental: Sabrina is a woman largely withdrawn from emotion and as a result is able to react in most battles calmly and efficiently, quietly working out ways to outwit her opponents. She's very disciplined mentally and highly intelligent. Her psychic abilities also gives her telepathic abilities as well. Generally she only uses them to share a link with her Pokemon, using her ability to command them without a word thanks to their telepathic link. With the help of her Pokemon, she is able to amplify and combine her powers with her Pokemon for a variety of abilities. Her psychic abilities are further used to determine the state of her allies giving her telepathic abilities some range. Although never elaborated on in canon, Sabrina's telepathic abilities would likely extend to humans as well (since her link applies to non-psychic type Pokemon as well). Her abilities would allow her to read the surface thoughts of others, but digging deeper would require a great deal more concentration.
==Weaknesses==
Physical: Without her psychic powers and Pokemon, Sabrina is just an ordinary woman. If you prick her does she not bleed? Although she may be used to avoiding attacks by Pokemon to some extent, any close combat fighter would be able to get the better of her without one of her Pokemon to amplify her abilities. Her psychic abilities are also powerless against creatures of darkness and ghosts, as well as constructs like robots. 
Mental: Due to her withdrawn emotions, Sabrina has difficulty expressing herself and her only real emotions tend to be annoyance, frustration, or anger. During those times she is in the least control of her abilities and were she left out of control long enough, she could possibly hurt herself or someone else as a result. Due to her quiet and secretive nature, she isn't given towards making friends or socializing with others. The only people she is known to trust are her fellow Triad members, Lt. Surge and Koga, and their leader Giovanni. She lacks empathy for others and although she is willing to do favors to those she considers 'allies', she's not taken towards doing things out of any sense of kindness.