I agree that some sort of level-based (i.e. score-based) matching is necessary. I also think that PVP is way more interesting than playing the AI, but I almost never PVP because I am a beginner at this game, and with a score of 250 I get matched with people of 2000-6000. It is really difficult to win the game if they use upgraded cards, but of course using hard point-matching is preferable to basing the matching on the presence of upgraded cards in the opponent's deck. If making top users unable to PVP is an issue, the matching could be optional, i.e. every user would have to enable score-based matching, which would be off by default. As a result, the top-level players would still be able to fight newbies who did not turn score-matching on for their PVP games.