Academically speaking, Dharma came to Shaolin in China to teach the idea of Zen. In order to exercise, he just invented some methods to guide health preservation. He doesn't know martial arts, let alone create the so-called eighteen bronze men. In terms of time, it is also untenable, because eighteen bronze men appeared in the Tang Dynasty, while Dharma belonged to the Northern and Southern Dynasties. They are hundreds of years apart, so he can't have founded the bronze man.