Conceding should only be possible in your own turn

I've played plenty of matches and I encounter a lot of players that concede when you're about to take out their pokemon and take the last prize card(s). This is so freaking weak and punishing for the other player because he or she will get less exp because of this. This is very toxic behavior and it needs to be stopped and I know how to stop it. Just make it so players can only concede in their own turn. And players who concede should be the ones to get punished, not the other player so the other player should get the full amount of exp when their opponent concedes.