Original Yang Taijiquan

Yang Luchan founded it after studying Chen style, the original style. According to this article, the 2-person San Shou was the original Yang form. When practiced solo it is referred to as the Pau Chui Cannon Fist Form. This article on the San Shou form agrees that it "may be an off shoot of the Pao Chui form of Ch'en style, as it has many similar movements."

Here is Gilman's 4-part instruction.