via facebook:

With the new Coliseum event in PeroPero drawing near, we thought we'd outline a few changes that have been implemented to keep the event competitive:Players will only be able to attack the same opponent 3 times in one day. After a user is attacked by the same player 3 times, that particular opponent will vanish from the player's list until the server resets.
The Overall Ranking system has also been overhauled. Overall Ranking will now be determined by Battle Points.The new formula used to calculate Battle Points will be: Attack x 3 + Defense x 1.
So prepare your decks and get your ladies ready for some competitive Coliseum action

As long as said changes are implemented smoothly, sounds like it should address the abuse problems from the first round pretty fairly.