Sauske had some training and got strong on his own, but he did take Oro's powers when Oro was too wak to fight against him. Perect stragety by the way. Who in their right mind would face one of the legendary sannin at the stage as a ninja? And he did receive powes from Itachi. Itachi gave him them powers wih the last few seconds of his life. Trying to kill Tobi/Madara/??? knowing he would try to reach Sauske. But yes, alot was handed to him. But he also trained and was strong. But what's going to be his powers after he gets Itachi's eyes!!! They have already been implanted.