Does the Griseous Orb boost Giratina's STAB move power AND change its form?

Question

Is it like the Lustrous/Adamant Orb, only with the form change, and with Dragon/Ghost boost?

Answer 1

May only be held by Giratina. When held by Giratina, transforms Giratina into Giratina-O. Raises the Base Power of Giratina-O's Dragon- and Ghost-type moves by 20%.
~Smogon

To answer your insecurities, yes, it will transform AND give the boost to it's Ghost- and Dragon- moves.

Answer 2

Yes.

Source