He was originally invented by Romeo as part of a plan to infiltrate HQ. Romeo intentionally made PJ Robot cute and friendly, so that way the heroes would like him and take him to their HQ. However, PJ Robot began to genuinely like the PJ Masks, and eventually betrayed Romeo to join them.
PJ Robot has the ability to hover above the ground, but additional details of its ability are currently unknown. It is presumed that PJ Robot can fly at high altitudes and speeds because of its wings.
In "The Mountain Prisoner", it's revealed that PJ Robot has at least four weapons installed in him, and can fight alongside the PJ Masks if needed.
In "The Wolfies Take HQ", it's revealed that PJ Robot can remote control HQ's rocket ship function.
PJ Robot is able to speak, though, his speech sounds muffled. However, he expresses his emotions by changing the digital face on his head. He is very friendly and energetic.
PJ Robot is shaped slightly like an egg and is white in color with a red trim design around its body and wings. It wears white gloves on its hands, and it has a clear dome for a head, with an aqua-colored digital face.