Just a quick fictional snippet on how I think a John Wick vs. The Punisher fight is gonna go. Also posted as a YouTube comment.
Wick would win the melee, but would not be prepared for Castle’s pre-rigged explosives. The explosion almost kills both. Punisher would drag himself up on a pier further down the river and spend some time in his hideout pulling out bullets. Wick would wake up in a hospital under police protection, and he would have to shoot himself out when some other enemy faction attacks the hospital under the assumption that the police holds The Punisher in that hospital. Then they would both, separately, attack a bad guy’s compound from two sides, working themselves in towards a crime boss that is a member of The High Table. In the end Castle will try to take another shot at Wick, but be distracted by his own conscience (we’re talking the Netflix Punisher, right?) and miss. Wick would run away rather than fight because time would be better spent hunting his actual enemies than fight this good-guy.