It breaks my heart when I see fishermen smacking octopus on the rocks. In Greece and other parts of the Mediterranean, octopus is traditionally tenderized by whacking it. Then hanging it out in the sun to dry. The drawback to pounding is that it produces deformation and breaks the skin and destroys the integrity of the octopus.
Think about it, would you take a steak and smash it to make it more tender?… the answer is definitely no. You would end up with pieces of meat that have had their appearance dramatically altered. So how can you tenderize octopus? One solution is put into the washing machine, but maybe that’s too much. So the best solution is to massage the octopus with salt until it becomes tender:
Here is another solution to making very tender octopus: http://mesubim.com/2013/09/12/octopus/
This helps break the collagen and provides a good result. Then hanging it is another matter, and that personal. The reason to hang it is to concentrate the flavors and make it easier to cut and serve.