I'm pretty sure this is Shade's Children by Garth Nix. From Wikipedia's description (emphasis mine):
Shade's Children takes place in a not-so-distant future where evil Overlords have ruled for fifteen years due to a catastrophic "Change" which caused all people over the age of fourteen to simply disappear. Since then, the children have been rounded up and placed in prison-like dorms. No child may live past their fourteenth birthday (known as a "Sad Birthday"), when they are taken to the Meat Factory and their muscles, brain, and other organs are harvested to create creatures. These creatures are servants of the Overlords, and as such both fight in the Overlords' ceremonial territorial battles and hunt for the rare escapees who have managed to remove the tracer implanted in their wrist. There is only one exception to this rule: some young women are kept for "breeding" to maintain the supply of children, until a suggested maximum age of eighteen.
Escape is rare, based both on courage and ability. These teens are gifted, however, with "Change Talents" - side effects of the Change that are unique to each individual and generally fall into the category of psychic powers. These talents are also dependent on Change Radiation, a mysterious field distributed by Change Projectors. This radiation allows the Overlords to control the weather and warp certain physical laws, which is critical for some creatures such as the Wingers, which would otherwise be too heavy to fly. The strength of the field is greatly weakened by water.
Several teams of escapees recruited by Shade live in a beached submarine, near a sewer pipe that allows access to an extensive sewer system. Shade is the only "adult" to have survived the Change. This, however, is mitigated by the fact that he is merely the uploaded consciousness of a real human scientist - a Dr. Robert Ingman. Shade knows that he is an uploaded consciousness and thus continually questions his humanity.
There are various Overlords, who have codenames such as Red Diamond, Gold Claw, Black Banner, and apparently originate from outer space. They fight each other in ceremonial battles in which all the soldiers are augmented humans - Ferrets, Myrmidons, Wingers, and so on - who seem more like robots or cyborgs (I think there's a revelation at some point that they were originally humans).
Each of the main characters was originally a child kept in captivity with a tracker in their wrist, who managed to escape before reaching the age for the Meat Factory, usually with the help of some psychic ability. One of them - either Ella or Drum, I don't remember which - visualised the tracker outside their wrist in order to remove it and escape.