It is not convenient to go to Zhangjiajie from either Emeishan or Leshan, so my suggest is take bus at Chengdu Xinnanmen Bus Station to Leshan Big Budda direstly (about two hours) and go to Emeishan late in the afternoon. Stay one night at Emeishan and see it the next day. Then suggest you get back to Chengdu and take a flight to Zhangjiajie. For Leshan/Emeishan is some 1000km from Zhangjiajie. There is no direct bus and train. Then you can take bus from Zhangjiajie to Phoenix City.