I presume it would be a pretty simple modification to make in the scripts. Just look at how the trainer battle script calls the VS Bar method, then add something similar into pbWildBattle such that if the encounter is for X Pokémon or while Y switch is active, then it displays the VS bar.
I found the solution.. I copied the animation section in the script and replaced the condition for its appearance with the switch, then changed the pictures and it worked.
Thanks anyway o/
Yes, I realize this is months old, but I would like to know where you found and inserted the code. I'm not very savvy with the code of Essentials, but I have been looking for a few days and cannot figure out where the code is. Please respond if you can help.