Name: 0927314 (just fucking call her Blue)
Superhero name: Blue Ribbon
Age: 17
Gender: female
Powers: an advanced shapeshifting- when she turns into a person, she receives their memories, secrets, and powers, but only for the amount of time she is them.  She can turn into things from her own imagination, as well, but the bigger the shift, the more energy it drains.
Backstory: her parents gave her up to a genetic study because they couldn't afford to care for a child. Eventually, she had enough, and broke out, slaughtering many of the scientists. And that's how Young Justice found her.
Appearance:

*a new OC half a year later- witness the change*
Name: Lacie Dunmark
Superhero name: Belladonna
Age: 19
Gender: female
Powers: can grow plants, can make people vividly hallucinate
Backstory: when she was six years old, she was kidnapped by Poison Ivy.  Ivy had heard that she had powers, so she did her best to raise her to hate Batman and Robin.  Unfortunately, Lacie had morals that couldn't be tampered with, and by the time she was fourteen Poison Ivy had abandoned all hope that she would ever be a good sidekick, so Lacie moved out and is now fending for her own.
Appearance:

Other: an antihero; the definition of antihero is not a villain but not a hero.  She's just a girl that acts in her own best interests using her powers, whether it means stealing a diamond or saving the world.