Ok, guys, I am trying to get Gary Oaks team. Even with his Pokemon's movesets! But, I only have XY, and it doesn't look like there is any way to get a Sky Attack Pidgeot in my game. PLEASE HELP ME!!!
Unfortunately not, as Pidgeot only learns sky attack via TM (generation one only) or Move Tutor (which you could do in ORAS, but not XY). Fortunately, as you can obtain one in ORAS easily by talking to a Move Tutor, you could trade for one.
In XY, you can't. However, there is a way you can get Sky Attack on Pidgeot on XY. If you have RBY on virtual console, and you have a Pidgeot in that game and teach it Sky Attack, then transfer it back to XY.