Warning: The following contains SPOILERS for The Flash season 8, episode 9, "Phantoms."
The Flash TV series broke its own rules regarding how potential superheroes might be found in introducing the character of Tinya, aka Phantom Girl. This point was particularly vexing due to the same episode which introduced Tinya also offering an explanation of how metahumans exist outside of Central City, which was then completely ignored by the action that followed. This point was further aggravated by the fact that the original Phantom Girl from the comics was an alien member of the Legion of Super Heroes rather than an empowered Earthling, making the complications of her origin needlessly pointless.
The Flash season 8, episode 9, "Phantoms" sent Iris West-Allen and Sue Dearbon to Coast City, chasing rumors of a ghostly metahuman dubbed CCP, the Coast City Phantom. Using a metahuman tracking app which measured the ambient levels of dark matter many metahumans left behind when they used their powers, the two discovered a teen runaway named Tinya, who had the power to phase through solid matter. By the episode's end, they learned of Tinya's quest to find her birth mother and resolved to help her.
Many found Tinya unengaging as a character, due to "Phantoms" not giving her any defining personality traits apart from wanting to be left alone and her backstory being related through an information dump delivered by Iris. There were also accusations of her being a rip-off of the X-Men's Kitty Pryde, due to Tinya also having the power to short out electronics that she phased through, which the Phantom Girl of the comics didn't have. The biggest issue, however, was that the metahuman tracking app shouldn't have worked on Tinya based on the information regarding her background revealed in "Phantoms" and the history of metahumans in the Arrowverse previously established in The Flash.
Phantom Girl's History and Powers In The Comics
To understand just how mixed-up the Arrowverse version of Phantom Girl is, it's worth looking at the character's comic book origins. Phantom Girl first appeared in Action Comics #276 in May 1961 and was created by Superman co-creator Jerry Siegel and artist Jim Mooney. A native of the planet Bgztl, which existed partly within the fourth dimension, Tinya Wazzo had the power to phase through solid matter, which was innate to her people. She joined the Legion of Super Heroes and used the code names Phantom Girl and Apparition while serving as one of the team's Espionage Squad.
A different version of Phantom Girl was introduced in the 2018 comic book series The Terrifics. This Phantom Girl, Linnya Wazzo, was an ancestor of the Legion of Super Heroes' Phantom Girl, who became marooned in the Dark Multiverse. She was rescued by the Earth heroes Mister Terrific, Plastic Man and Metamorpho, and stayed with them rather than return to her home planet, due to her powers having become unstable after so many years spent in an intangible state to avoid the perils inhabiting the Dark Multiverse.
Both versions of Phantom Girl had the same power to make themselves insubstantial. The Tinya Wazzo Phantom Girl also had the ability to safely enter and exit the extradimensional plane known as the Phantom Zone at will. Linnya Wazzo lacked this ability, but could make solid matter explode when she touched it while in a solid state. This was less of a power, however, and more of an unfortunate side effect of her time in the Dark Multiverse, which Mister Terrific attempted to cure.
The Problem Posed By The Arrowverse Phantom Girl in "Phantoms"
The Phantom Girl introduced in The Flash episode "Phantoms" was also named Tinya, but was said to be a native of Coast City rather than an alien from the planet Bgztl. She was presumed to be a metahuman, which is the technical term DC Comics applies to Earthlings who develop superpowers. Sue Dearbon explained the history of metahumans in the Arrowverse early on in "Phantoms," describing how metahumans are created when people with certain genetic markers (or metagenes) are exposed to the right set of traumatic circumstances, triggering the spontaneous development of superpowers.
Most of the metahumans featured in The Flash were created by the wave of dark matter unleashed by the 2013 STAR Labs particle accelerator explosion in Central City, but Sue specifically noted that she had "run into quite a few metas around the world" while hunting the Black Hole crime syndicate. It was also implied that metahumans were rare outside of Central City, given that Tinya was the first metahuman reported in Coast City. While it is unknown how big Coast City is in the Arrowverse, it appeared to be a large city and Green Lantern (Volume 4) #50 reported the city's population in the comics as 2,765,321.
The problem lies in Iris West-Allen and Sue Dearbon finding Tinya using a method that had been developed to track metahumans based on their dark matter signature. Iris specifically told Tinya that "metas like you are made up of dark matter" and explained how they used the app on her phone to find her. However, only those metahumans created by the STAR Labs particle accelerator explosion have a measurable dark matter signature. This point was previously outlined in several episodes of The Flash, most prominently in the case of Frost and her father, Dr. Thomas Snow, who both gained ice powers as a side effect of an experimental cryogenic treatment for ALS. As a result, Frost was the only member of Team Flash able to use their powers against both versions of the power-negating villain Cicada, whose abilities only effected metahumans created through exposure to dark matter.
How Making Phantom Girl A Metahuman Is Better For The Flash
This begs the question of why The Flash should bother to make the Arrowverse version of Phantom Girl a metahuman rather than an alien. The simple answer is that the various Arrowverse series tend to focus on certain aspects of their shared reality, such as Supergirl dealing with alien threats while Arrow centered around street crime. Since The Flash introduced metahumans into the Arrowverse, it makes sense that the show would want to stick to its brand, even when there's nothing to stop Tinya from being the daughter of an alien immigrant to Earth like many supporting characters introduced on Supergirl. Unfortunately, The Flash has already sabotaged this far easier explanation for Phantom Girl's powers by forgetting that not all metahumans are created by dark matter.
The Flash releases new episodes Wednesdays on the CW.