I haven't tried QGJ (I only have him at 3 stars and he stinks at 3) in PvP but I guarantee you a lot of those fights will be all or nothing if you are really counting on that Stun. So just be aware that you will encounter frustration.
Personally I run a 7* Luminara and she hits HARD and has an Abilty Block. She acts right after Eeth, so if his Stun fails, then I can at least Ability Block (or kill) whoever I was most afraid of. That 1-2 punch means the #1 threat is removed 100% of the time, every fight.*
* Barf Sidious excluded. He's too frustrating to whiff on so I take care of him #2-#5, and usually #4 or #5. It sounds crazy but he doesn't tend provide synergy (offense, yes, synergy no) to his AI team and you can deprioritize (sometimes even ignore) him in Arena. Not GW where healing is crucial, of course.
** Again, see SWGOH Cantina.