Sonia Shields is an eighteen year old girl living in Starview Heights. She is the daughter of Captain Shields, and lives with him and his two surrogate children, Colin and Colleen. Formerly a teen popstar, she now fights as Buster Pink of the Power Rangers: Spy-Busters.
The only child of Captain Logan Shields and his late wife Barbara, Sonia had a very happy childhood, despite the fact that her mother died when she was only five. Two years later, Logan took in Colin and Colleen Voice after their mother was killed during Psycho's rampage, thus making them Sonia's surrogate siblings. Sonia exhibited a talent for singing from a very young age. At age twelve, she was discovered by an agent working for a record label; she was quickly signed and moved away to Los Angeles to become a popstar. She spent the next several years there, rapidly growing a devoted and loyal fanbase and becoming quite the celebrity in the process. However, one day that all changed. During a routine concert at the end of a long tour, a near-death experience occurred, triggering her metagene and causing her to develop the meta-ability of Flight. The fans in attendance turned on her, forcing the record label to essentially fire her. Sonia, who had been considering leaving anyway, flew back to Starview Heights to live with her dad again, much to his surprise and delight. Now, she serves a new purpose-fighting alongside her surrogate siblings and new friends as Buster Pink!
Sonia is a very sweet, albeit ditzy girl who loves music, nature, and shopping. She is very outgoing, and has an unbelievably big heart. Although she can be kind of a ditz at times, at others, she shows that she is wise beyond her years. Despite her previous status as a world-famous popstar, Sonia is very down to earth; she treats everyone around her with respect and doesn't look down on people for not being famous. In fact, she does quite the opposite-Sonia constantly doubts her abilities as a Ranger, a student, and as a friend due to her inexperience and unfamiliarity with normal teenage life. Despite them not being her real siblings, Sonia shares a deep bond with Colin and Colleen-especially Colin, whom she secretly harbors a crush on and has for many, many years. She is very protective of the twins, values their opinions over anyone's else's, and considers them her two best friends in the entire world.
Morphin' Brace V2-Sonia's morpher. It is an upgraded version of the morpher used by Graham, Colin, and Colleen and allows her to morph into Buster Pink.
Spy-Blaster V2-Sonia's primary blaster-weapon. It is an upgraded version of the Spy-Blaster and fires in three-shot bursts as opposed to semi-automatically.
Spy-Saber V2-Sonia's primary sword-weapon. It is an upgraded version of the Spy-Saber and has the ability to electrocute her foes.
Flight-Sonia's meta-ability, which she developed after a near-death experience triggered her metagene. Using the Enertron in her body, Sonia can envelope her body in an aura of energy and subsequently use it to take flight. Her Weakpoint is yet to be discovered.
Ultra-Hearing-A secondary meta-ability of Sonia's, which was first discovered during the events of "Proving Ground". Thanks to the Enertron flowing through her veins, she can focus her hearing and clearly pick up sounds from miles and miles away, much like an owl.
-She is the first Ranger to be a famous musician prior to joining her Ranger Team. (Kira Ford of Dino Thunder became a famous singer after the events of her season, whereas Sonia became a Ranger right after retiring from her career as a popstar.)
-She is the first Pink Ranger to not be a member of the core team.
-Unlike her teammates, Sonia has no Sentai counterpart-at least, not in the traditional sense. There was a "Pink Buster" in Go-Busters, but she was a Wannabe Ranger and had no suit nor any powers. (This technically makes Sonia an American-exclusive Ranger.)