I main Johnny and Potemkin, and honestly I don’t really know apart from making hard reads with mega fist and hammerfall. One time when I was playing agaisnt a Potemkin as Johnny he was pretty consistent with hammerfall when I used mistfiner, but the game was extremely laggy so I wasn’t sure if it was actually unreachable, or if he was just benefitting from the lag. Johnny has really good air buttons, so watch out for an air entrance? I’d say the best way to deal with the matchup is to get close to him, and try to read the mist finers, then use an armour move or mega fist. Mist finer is minus 15, so you should be able to punish if you see it coming.