While you are chaining the Pokemon, a Pokemon with the ability Damp will prove helpful to you. The ability prevents all Pokemon on the field from using Explosion or Self-Destruct completely, as in the moves will fail entirely and the Pokemon won't faint. You can catch a high-level Golduck at Poni Gauntlet to get a Pokemon with the ability quickly -- you'll be able to tell when they have Damp as soon as you enter the battle, since their other ability Cloud Nine is always declared at the start of battle. Also, maybe try chaining Geodude instead; they're weaker and will wear down Golduck slower than Graveler will.
Thought I'd also mention breeding as an alternative to chaining that you might find more useful. Using Masuda method (and especially Shiny Charm on top of that), your chances of hatching a Shiny are better than your chances of finding one with a 70+ SOS chain (roughly 1/683 versus 1/1024). In addition, breeding lets you control factors like IVs and nature more easily, and allows you to get the Hidden Ability more often (15% while chaining versus 60% to 80% while breeding depending on the parent's gender).
The process I would use would be to chain repeatedly using Golduck until you find the first Geodude with Galvanise. (You can check for the ability using a Pokemon with Trace, Worry Seed, Skill Swap and the like, though Geodude might explode on you while you do this.) Once you've done that, you can start breeding. Make sure you pair Geodude with a Pokemon of a foreign nationality to trigger Masuda method chances, and if you're not breeding with Ditto, that Geodude is the female in the matchup so it passes down the species.
Unfortunately this sounds like a very difficult Pokemon to chain and breed, let alone to get a Hidden Ability and Shiny trait onto -- remember it's impossible to guarantee either trait with any method, so you could potentially hatch a Shiny Geodude without Galvanise. Good luck with it though, I've hatched some nice stuff myself with some patience!
