Here's a Physical gastrodon set to make up for his defenses. For an ability, you could go with Sticky hold in the event of a pokemon trying to use trick, but aside from rotom, that doens't come up very often. I prefer a special bulky Storm drainer, but this can work too. This set helps compensate for his low defense, giving you a bulky, high HP pokemon with fire and rock resistance, as well as an electric, and possible water immunity.
Curse-boosts up defense and attack.
Recover-Restores health.
Waterfall-STAB; gets a curse boost.
Earthquake-STAB.
If you don't like these moves, you can also make use of Body Slam for a possible paralysis, stone edge to hit flying types.