I did a forum search and couldn't find one with the following parameters:
No prep. PIS and CIS on. In-character, so yeah, they're probably going to be out for blood (but they are technically not bloodlusted). Whatever is standard for both suits of armor. No prior knowledge of the opponent other than they know each other's name and what the other looks like. No outside help and BFR is not allowed. The battle takes place in the skies over Metropolis devoid of superheroes, but full of bystanders. While a kill counts as a win, KO also counts as a win. If someone flees the battle or surrenders or whatever then they lose. If someone is incapacitated for at least 10 seconds that counts too.
Who and more importantly why?