Combiners
One of the most powerful weapons developed during the Great War, combining technology was based on the principle of joining several troops together and multiplying their power beyond the sum of heir parts. Decepticon leader Megatron initially commissioned his chief scientist Shockwave to develop the process, experimenting on the Constructicons to create Devastator, the first-and most feared-of the gestalts. The secrets of the process were part of the escalation in military technology on both sides as the war progressed, with the Autobots developing their own combiners and the Minicons using their own variations of the technology based on stolen research from the Autobots.
Not all Cybertronians are suitable for the combiner process; during Shockwave's initial period, many unfit mechanoids were driven insane or rendered permanently inoperative. Much like the triple changers, there must be an inherent predisposition that's encoded within the candidate for the process to be a success. Once a group is selected that matches the qualifications for physical and mental combination, their combiner gene is activated, reformatting their bodies to combine into a unified robot form. Physically, the combined forms are designed to maximize the energy output of all the components; this leads to gestalts that are far more powerful than the sum of their parts might imply.
Although the impressive physical properties of the gestalts are well known, the details of their mental unification are more poorly understood. It is known that the individual minds are submerged into a single unified personality; however, this personality is generally limited in its cognitive and creative abilities by what the team members can subconsciously agree upon.
It is rare but possible, for a gestalt to have its own highly intelligent and well developed personality, but this only occurs in cases when the team's attitudes, attributes and goals mesh (Ex. Include the Street Action Team's Centurion). Most of the time, gestalts are the victims of their fractured personalities, making them unstable and dim (like the Constructicons' Devastator and the Aerialbots' Superion).