Joystick is a reasonably strong fighter. She has some basic super strength and speed at her disposal. That being said, she won’t be able to keep up with Yang. Yang’s berserk mode will definitely improve her physical abilities past Joystick’s level. Yang’s projectiles are also fast enough to force Joystick to keep her distance or risk a quick defeat. Yang wins.
Suggested by iKnowledge Joystick is a pretty good athletic fighter. She has a degree of super strength and speed that is on par with a Scarlet Spider. She is a formidable fighter and while Harley Quinn is skilled as well, her attack power is nothing special. Hand to hand combat might be Harley’s only edge, but I don’t think it can compensate for the gap in strength. Joystick also knows the basics of hand to hand as well. Joystick wins.