XJ-2 is an XJ prototype robot that works as some sort of a ray gun. Her biggest defect is that she suffers from uncontrollable hiccups and accidentally shoots plasma beams out of her nozzle-like mouth.
- Sibling Tsunami (Her first appearance)
- Sister Sledgehammer (She, along with XJ-4 are the first two XJ robots to be absorbed by the Cluster-possessed Jenny but is later freed)
- Agent 00' Sheldon (No Lines)
- Escape from Cluster Prime (Brief Cameo)
- Labor Day (Brief Cameo)
- XJ-2 does not talk, but she indistinctly utters the word "hiccup" when accidentally shooting out her rays.
- Her voice actor is unnamed in the credits, even though XJ-2 does speak this one word.
- She is reminded by Dr. Wakeman in Sister Sledgehammer to hold her breath so she can control her ray blasts, but this only causes her to backfire (explosively fire her laser from the back).