It's allowed. People go even further to sell CPQ leech, where people make specialized level 50 characters to leech other characters inside the PQ (you can buy an Everstone from the cash shop to prevent exp gain.) Some may say it's even part of the nostalgic experience of CPQ
People literally only trade win if they aren't leeching, just a head up lol edit: LPQ leechers also trade wins too. The common norm on the lose leech team is for the leader of the winning (usually the leecher) party to leave so that the other party can get the 30k EXP. You tend to get get more than 60-100k EXP per leech anyway, so the 30k end is irrelevant.
I'm not sure about other CPQers, but I do trade wins even when selling leech or helping a friend with leech Also, I am against the scamming of CPQ wins (running away upon winning the round)