Yup, you're right, Pert's physical movepool is like EQ, Rock Slide, Return and.... a physical Hidden Power of choice. lol I'll get it Brave anyways, and your Sassy suggestion convinced me so i'll be getting it after i RNG a couple of 3rd Gen goodies for 6th Gen. Thank you! :]Personally, I love pokes that set up curses (ex. I soft reset a great Iv careful registeel that absolutely wrecks in the frontier). I would recommend sassy, just because swampert could use a water/ice move as coverage, even if they weren't boosted by curse. Another nature could be brave, as a offensive swampert would be amazing, but it needs to use hydro/surf/ice beam as extra coverage (swamperts physical move pool kinda sucks in gen 3 :()
Just my opinion :3