I just faced a team way weaker than mine with just weak silver and bronze characters, I was able to defeat his entire defenses but when I went to see how he was doing against my team he defeated all of them, even the boss battle, in just one try. In a lapse of less than 20 minutes he was able to defeat without loses all my team with his way weaker team. There's a possibility that he was really skilled but even so the speed of his victory is really suspicious, so there might be a chance that it could be a cheat that give him an increase in his stats.