I'm trying to scale a standard medium creature into a gargantuan sized version. The size increase tables don't seem to cover it well, though I could just be missing it. What stat changes should be made to reflect the size increase?
You would apply the stat increases for medium to large, then large to huge, then huge to gargantuan. You should also give it some more hit dice until its hp and attack are close to the average for the CR you want it to be.