I have run into someone with the PSN ID Mynus, and it was a really good Carl. I'm not sure if it's the same Mynus 10stars mentioned, but, I did pick up a few things...
-In the first moment of most matches we had, this Carl played it safe. He liked to hide behind Nirvana, who will soak up any drive nails. I found that to be really annoying. At first I charged in to put the pressure on as soon as I could, but I usually just ate an attack from Nirvana. I tried baiting an attack from Nirvana and then attacking Carl instead and had loads of more success, when it did work.
-This Carl player liked to do this approach from fullscreen. Nirvana would wind up and do a lunging punch while Carl would air dash over Nirvana's head, using his multistab special (I'm not too familiar with Carl's movelist, sorry). It really pushes back the guard libra if you try to block it, so I usually threw drive nails from above to get him to stop. Looking back I think countering with 5d and then teleporting with A might have also worked.
-I tried to separate Carl from Nirvana asap, usually with a bnb that ends in 623C. Without Nirvana he was pretty much helpless to anything I wanted to do; j.c, j.4c, 2a, etc. I just kept mixing it up and he couldn't do much about it except guess or die. On the other hand...
-When I can't separate Carl from Nirvana I had a tough time getting the momentum on my side. Don't EVER get stuck between Carl and Nirvana; it's exactly where Carl wants you. Whenever that happened to me I was pretty much screwed unless I could time a lucky guard point or jump out. Also, clap loop hurts. Be wary for throws and its setups
-Carl's hitbox is small. I wiffed with 5a or C nail a few times and it cost me. I'm sure better Bang players won't have this problem, but it aggravated me...
This Mynus and I played about 5 matches. Not many, but this is what I gathered from them. Hope other Bang players can learn and improve on it.