EDIT In Defod, there is no need for object pools for perf reasons. The advice below is meant for when you for some reason want to have an object pool for your particular game design. There is more info on the perf side in this other thread.
EDIT2 If you do want to have a large number of lua objects (tables, vectors, etc) alive, it might in some cases be wise to put them in an object pool for perf reasons. But it does not apply to game objects, which are very cheap to create/destroy.
I’m not sure I know what you mean by object pooling, so I assume you mean keeping a bunch of objects that can be acquired/released? You can use the lua datastructures for that, e.g. the table. Probably plenty of examples on the web. From the top of my head, I would suggest you use two tables, one for free and one for acquired objects. If you want to put game object instances in it, you can index the tables by the id of the game objects and then you just need to move them between the tables.