gym battle

quoted from the WIKI " It is filled with trainers, one of whom is a Gym Leader who rewards the player a Gym Badge and a TM once they are defeated." but where is the TM that is given defined. the example gym in essentials does not have a normal give item script.

All you need to do is have it call the "Give Item" script sometime after the battle ends, but not before the player leaves.
It should look something like this I'd suppose

add Kernel.pbReceiveItem(PBItems::X) in a script command

X is the item you want the player to get,you can look up what you need to replace X with in the editor by scrolling to the item or by looking in the right .txt file in PBS

Derxwna Kapsyla already showed an example above

thanks guys. I wasnt sure if there was an internal script which automatically did this with gym leaders.