WaU Chica is a variation of Chica that came about during 2103 when the Warden Unit tried to resurrect people through the animatronics.
WaU Chica appears to be the normal Chica, but one of her arms has become one giant growth, but she can still move it. The cupcake is part of this growth, the only recognizable part of it being part of the candle. The tops of her legs are fused together by WaU tendrils, making her the slowest of the bunch. Her bib is unreadable due to a large growth covering her torso. Both of her eyes are replaced by small growths, causing her to have a blue tint in her vision.
A day before January 12th, 2103, what was left of Fazbear Entertainment snuck their animatronics along with other animatronics from other companies into PATHOS-II undetected. On March 9th, 2103, the WAU's influence reached the animatronics, causing them to activate. In this timeline, Freddy, Bonnie, and Chica are the reasons why things went to hell at Upsilon. Chica was put in Upsilon's shuttle station. When Amy Azzaro came into the room Chica was in, the robot lashed out, mortally wounding Amy. Chica then calmly strolled away, looking for something else to do.