Press F8 while in-game and select save pet team. This allows you to save your pets so that other people can fight them in the pet arena. If you don't know what I'm talking about then go to the pet arena and select the Extra teams. Those are player teams from before the server was disabled. If you want to fight other player's teams then drop their .pet file into your /user/ folder.
We have yet to confirm whether or not Custom AI carries over games, so if you use Custom please take the time to post your .pet file here.
You may fight this team by going to the pet arena and selecting: "DotPetFile..."