For carl you can just do the standard BnB, but limit it to two j.9d~6s. Thats about the only thing you can do off of 6C on carl that's easy to execute. As for 3C combos, the one you mentioned works fine on him and almost all of the other cast, and if you use a taunt instead of 5c then you'll get better damage output than the standard 3C combo.