Transformation
Transformation is the process by which a Transformer alters his form between modes. It should not be confused with reformatting, a type of full-body upgrade.
The technical details of transformation, as well as the manner in which the art was introduced to the Transformers themselves, vary between continuities. When the issue is addressed at all, transformation is usually treated as an innovation from some point early in Cybertronian history rather than something that was literally always with them. The Transformers were, at the time of their genesis, simply Cybertronians -- mechanical life-forms -- and became "Transformers" only later. However, just as often in Transformers fiction the "origin" of transforming is simply not discussed.
In most continuities, transformation is not a trait limited to Cybertronians. Both sentient alien races (such as some portrayals of the Lithonians) and animals (such as the lipoles on Jupiter's moon Io) exhibit the same ability. The Quintessons also incorporated transformation into some of their later creations including the Sharkticons, Allicons, and Overcharge drones. Some examples of transforming robotic aliens, however, can be traced to colonization in the distant past by Cybertronians. The G1 planet Paradron, as well as the main planets in the Cybertron franchise are examples of this.
Special transformation types
High-speed transformation
Some Transformers, specifically the Autobot Jumpstarters and the Decepticon Battle Chargers, are specifically designed to transform much faster than ordinary Transformers, usually taking less than half of an Earth second to switch from robot to alt-mode or vice versa. How much this ability depends on physical versus mental capabilities is unknown. In the Dreamwave G1 continuity, Triple Changers were also stated to have unusually fast transformations (roughly twice the normal speed, whatever that is).
Multiple alternate modes
Robots with multiple transformations (Triple Changers, et al.) are a special case. Though there seems to be some aspect of natural aptitude at play in one's ability to master multiple forms (for example Dreamwave comics referred to a "genetic potential" within the sparks of such robots), and of course the special physical construction granting those forms, the balance of the matter seems to be one of training. Most Six Changers are said to have mastered their plethora of transformations through rigorous study. The largest number of modes exhibited by any single individual is RID Galvatron, who had ten.
Adaptable bodies
Some groups of Transformers such as the Go-Bots use a process similar to reformatting to more radically alter their forms while transforming. This ability to start with one robot and alternate form and transform easily to entirely different variations without extensive mechanical work comes from unique metals in the Go-Bots' bodies, and does not apply to most Transformers.
In the G1 continuity family, the Action Master Skyfall appears to possess something akin to this abillity.
Transformation cogs
In the G1 animated series, the city Transformers Metroplex and Trypticon are both specifically stated to possess devices known as transformation cogs that somehow control their transformation processes, and are essential to allow them to transform at all. Such cogs are rarely mentioned elsewhere in the fiction -- even in other continuities -- so it is not clear if all Transformers require them, or Metroplex and Trypticon are special cases, perhaps because of their size. However, one other example is that Nitrostreak ("Unit One" of the Maximal Command Security Force) had his cog damaged in a firefight with Megatron's henchmen. Dawn of Future's Past Since this story takes place in an unknown Beast Wars setting, and the Beast Wars cartoon itself takes place in an amalgamated G1 universe, the larger significance of this event is up for debate.
Fiction
Generation One
Marvel comics
Unicron was the first Transformer, fashioning his metal prison into a robotic semblance of his original form. Primus, watching from a distance, was all like, "Oh snap, robots that turn into things? Why didn't I think of that?" and quickly trained his own children to do the same thing.
Some accounts credit the development of transformation to Megatron and the Decepticons, with the Autobots later copying the technique. This, perhaps, implies that the potential for transformation instilled by Primus was dormant until Megatron realised it, or that it was forgotten and rediscovered at some point.
Animated series
Transformation was an Autobot innovation, developed during their first war with the Decepticons when it became apparent that they could not match their firepower and strength. The art of transformation allowed the Autobots to disguise their forms, thereby allowing for stealthy attacks on their enemies. This strategy met with great success, and the Decepticons were defeated, allowing the era of peacetime known as the Golden Age of Cybertron to settle in. The Decepticons subsequently adopted transformation technology themselves, coupled with robot-mode flight powers, and re-ignited the civil war. (See "War Dawn".)
Transformers generally seem able to shift modes at will, although in cases where they have suffered severe physical injuries, transformation is sometimes a strain. In one case, and one case only, a Transformer indicated that staying in his altmode was too energy consumptive, and had to revert to his robot mode: Warpath, when trapped in midieval England and low on fuel. Decepticon Raider... This problem seems to almost never come up, even in cases where Transformers are very low on energy, so its significance is unknown.
Beast Wars and Beast Machines
Beast Wars-era Transformers have their transformation sequences controlled by the same onboard computers which manage a variety of other body functions, such as stasis lock. Transformation is triggered by a command to this computer, usually done by voice, but sometimes with a thought. These computers may have been a part of the Great Upgrade, and once activated they coreograph the shifting body parts, allowing the Transformer to continue to concentrate on other matters.
This advance implies that transformation may be a mentally rigorous task, at least in the sense that it requires a few seconds of concentration. Post-reformatting, the new technorganic forms granted to Cybertron's inhabitants lacked on-board computers, requiring them to re-learn the mental disciplines involved. It may be that a technorganic transformation is more difficult even than a traditional transformation, as the reformatted Maximals often reverted to their beast modes upon losing their concentration or emotional "center". This notion that the transformed state requires constant effort may be related to Warpath's statement about his tank mode consuming more energy (mentioned above).
