Is it Normal STAB because it's a Normal move, or is it for the move it turns into? For example a Ground-type Pokemon using Nature Power in a wifi battle turns into Earthquake, would it get STAB?
http://bulbapedia.bulbagarden.net/wiki/Nature_Power
Nature power turns into a move based on where you are, thus changing its type to whatever. Like MewCreation said, the STAB will be for the move that it turns into.