I've made a pet battle AI/back end. It should be reasonably accessible if you are used to running windows console programs. The source code is here
and the executable and data files can be downloaded here
Right now it is moderately useful if you want to figure out which winning percentages for a particular team vs team match-up. The UI leaves a lot to be desired and I would l would happy if someone wrote a real one which can attach to this back end.
I plan on significantly improving the AI. It employs a simple alpha-beta search for a zero-sum simultaneous move game with perfect information. The perfect information is misapplied here since in a real pet battle neither player knows their opponent's ability selections at the beginning of the game. I anticipate that using Monte Carlo techniques will speed up and improve the AI.