The AV-98T Dolphin is a training use labor based off of the AV-98 Ingram. The Dolphin contains all of the Ingram's advanced propulsion and sensor equipment, but lacks much of its armor and weaponry in order to minimize cost.
Seen In episode 2 of the TV series, these were used in a tournament style setting to determine who would be the pilot of the new AV-98 Ingram. Fortunately, though Kanuka Clancy won the fight at the end between her and Izumi Noa through a last-ditch move, Noa was declared the pilot of her AV-98 Ingram, whom she personally refers to as "Alphonse" due to Clancy's status as a temporary officer at the section 2 Headquarters, thus preventing her from staying, and therefore being a pilot for the Ingram. As a minor note, Shinohara Asuma was assigned to another Ingram that was acting as a backup unit, along with Isao Ohta.