End of series Sakura.
OT: Pain.
Sakura has great physical strength and healing; however, her game is ultimately hand to hand combat, and she lacks the speed to land the hits needed to KO Pain. Summons were seen to be worth next to nothing between Pain's own summons and Shinra Tensei.
Between the combined moves held by Asura, Preta, and Tendo.... Sakura's fighting style is rendered useless. As a speed Taijutsu is ultimately needed for Tendo such as the 8 Gates. Sakura focuses on power which doesn't cary as much weight as it normally would.