PCGen 5.17.16 + PFRPG + APG + Bestiary
Bestiary for Cloud Giant (p.147) states "Oversized Weapon (Ex) A cloud giant can wield Gargantuan weapons without penalty. Most favor the use of immense morningstars."
An equivalent statement is made for the (Large) Ash Giant: "Oversized Weapon (Ex) An ash giant can wield Huge weapons without penalty."
I believe the Bestiary is clear that this applies to any oversized weapon wielded by such a being.
However PCGen allows only one application of the ability, and choice of one weapon.
Windows, Java 6, PFRPG + APG + Bestiary
Completed: At revision: 17324 - No Choices Required, All Weapons of One Size Larger are allowed without Penalty. Does not affect same sized weapons.