Right now, every wild battle/npc battle you start, your opponent will already be dead.
This is really weird and stupid, but i guess if you hurry up you can get some quick achievements from it.
You won't get xp, you can't catch any pet, but you get the "wins" from the battles.
Update:
In pvp, both you and your opponent will get 97 hp, 0 attack and 0 speed on all of your pets. It is impossible to win or lose.
Update 2:
If you wait long enought for your opponent to leave, you get full xp for the fight.