she can be defeated member when she fought against orochimaru? she kept pounding at her and making her use all her energy and it made her use that energy she stored up in her forehead then she uses it up and she runs out of energy. My best guess is that if you cant get her with your ninjutsu and genjutsu then make her use up all her chakra and then attack her after she uses it she is able to be defeated she is not Immortal she can die she just is one tough woman and can take it hard when the time comes. she is tough and she is only legendary cause of that strength, yet it has a weakness.. her body needs the energy to produce such immense amounts of strength same with sakura thats why they get massive ammounts of chakra reserves and it is used on there physical capabilities. that or they can train normally like Rock lee and get power that way. lee is almost as powerful as sakura and Tsunade yet he cant use anything but taijutsu he is Kick ass. anyway she is defeatable member that Jiraya is the best of the three he is the most power of the legendary sannin.