are we able to transform and deform body or hands of G3 character? I know we can do that on the facial expression, but I cant find anything related with the body part

I suggest that if you want to edit motion and the motion must be had transform and deform body, you could use G2 Character.
Because of G2 character has more motion that is G3 character could not achieve such as 3D Motion, the body rotate, etc.
You could be thinking which character could complete your animate and which motion suit type character.