I use "GML1_FACE_Blank.anim_pc" and rename it to whichever animation I want to replace. It's a facial animation, so there's no body animation data. The result when used in place of a movement animation is a T-Pose. I've attached a replacement for the default Standing animation ("GML1_BS_SD.anim_pc"). This will also apply to most NPCs, but some other NPCs use different Standing animations, like "PFL1_BS_SD.anim_pc".