Mother and Father

and were the first two puppets Sasori ever created, modelled after his real mother and father, who were killed by Sakumo Hatake during a war.

Background
Losing his parents to Sakumo at an early age, Sasori became forever plagued with the melancholic loneliness of lacking parental love. When his grandmother, Chiyo, introduced him to the Puppet Technique in hopes of cheering him up, Sasori went and created the Mother and Father puppets in an attempt to simulate the parental love he so richly desired. The empty and lifeless puppets could not fulfil that purpose, and a disillusioned Sasori eventually discarded them when he left Sunagakure. With his departure, the puppets came into the possession of Chiyo, who modified them for combat purposes.

During Chiyo's battle with Sasori many years later, Chiyo uses the puppets against Sasori, although he easily disables both with the Third Kazekage puppet's Iron Sand. After the Third Kazekage was destroyed and the Iron Sand's hindrance was nullified, Chiyo uses the puppets to stab Sasori through his core in the form of a hug, allowing him to be close to them in death as he couldn't be in life.

While Sasori's soul was being released from the Summoning: Impure World Reincarnation technique upon learning that they and his remaining creations actually had immortalised him, Sasori handed down his Mother and Father puppets to Kankurō, and asked that he entrust them to future generations as well. In the anime, Kankurō employed those puppets against a reincarnated Chiyo, having recovered them at the occasion when he procured the Sasori puppet.

Abilities
Originally built to comfort himself from his loneliness, Sasori did not install any weapons or combat capabilities in the two puppets. After he abandoned them, Chiyo eventually made several modifications to the puppets, such as adding weapons, so that they could be used in battle. Both have a chakra shield installed in their arms, as well as razor wires that they link together with their fingers for cutting. The Mother puppet wields a serrated katana, while the Father puppet wields a segmented wooden whip covered with kunai. In the anime, Kankurō further modified the puppets, adding a cable, just like the Sasori puppet's, to both puppets.

Trivia

 * In Naruto video games, the puppets are commonly used as Chiyo's main method of attack.