Man of Science Who Wields the Living Lightning
I play both characters but I've only played the MU once and lost. I don't think it's to bad for us. We can discharge punish a lot of his strings but we have to guess whether or not he lets boxing gloves rip (I'll have to test if BF2 jails from strings since iirc it's a high). If he does F14~BF2 at close range we can still punish so there's that. Unfortunately he out-damages us and F14 and F21 are harder (-ish??) to whiff punish but we have F11 and B12. In the corner Joker is only 0 on advantage so I think wake up buttons is an option we cannot ignore. I think utilising D4 in the neutral to stuff his F2 attempts is important as it sets up our F4 as well, and we can easily trip guard his JI1. From full screen I think he holds slight advantage since all his projectiles knock down and he can set up massive plus frames off BF4 AMP (bouncing jack in the box), but it's not that we can't contest.
EDIT: we can also BF3 UNDER Joker's BF1 projectile. Flying out of the corner is also a viable option for us to escape pressure. This guy also has superb conversions off of his F3s and F2s. Throw techs are on point as well.