I haven't done this simply because I don't know if it is against the rules.
I have done some PvP and after a win the wheel spin has items that were in your opponent's deck (obviously). In theory, I could load my deck with the best upgraded rares that I have regardless of their viability and lose on purpose solely for the purposes of giving people a shot at the best stuff in the game (improved miracle, towers, supernova, etc). I do agree that this is a little unfair or goes against the grain of the game but most card battle games allow for trading and it's not as if the process I described would allow for easy instant trading.
I'm loving this game and look forward to an update. I'll be sure to donate a decent amount to help that process when I get my next check.