I agree with you TSquared and Meorawr.
About the battles themselves, this is how I see it; the server receives the action you wish to take and returns the client the outcome, as soon as you have sent your action an event fires to tell the client the result. This is why you can win a pet and get the quest completion screen at the start of the round and not have to wait for the end, because the game already was told what happened.
So it's safe, just client side visuals and such are handled by the client. In reality you can have a "skip animations" option to turn off all visuals for pet battles and just tell you the results as soon as they are received from the server, seconds after you have chosen your action.
