Medachange (メダチェンジ) is a transformation act that some Medarots can perform.
A Medachange can only be achieved by some Medarots that have been built to perform said action. When a Medarot performs a Medachange it will undergo a physical transformation, with the consequence that the Medarot won't work under the four Parts architecture while the transformation lasts. Thus, any damage the Medarot receives will affect its whole body. However, the Medarot will be as resistant as it was before the Medachange.
Attacks and Actions in a Medachanged Medarot
A Medarot that has Medachanged will have three actions available for it to use, like its previous form. These actions are called Drives (ドライブ): Drive A, Drive B and Drive C. Each Drive action will allow the Medarot to perform a certain action not limited to a certain part of the body, like it was for its previous form. For instance, Brave Police's Medachanged form allows it to either shoot a Rifle attack or a Gatling attack from either arm, or use both arms as Swords to strongly strike an opponent Medarot.
Some Medarots that can Medachange will perform exactly the same actions it could do before the Medachange. One example of this is Blackbeetle.
Other consequences of the Medachange
A Medachanged Medarot will entirely change its shape. This does not limit the change to the actions it can do, but the way the Medarot mobilizes. This means the Medarot will also change its leg type to another one, depending entirely on how the Medachange was designed. For example, Saikachis's Medachanged form is a Vehicle, while its regular form is Bipedal. This change also allows the Medarot to be somewhat more adaptable to different terrains. Others, just like Diststar, keep their leg types.
Usually a Medarot that is able to perform a Medachange is less resistant to another one of its same series and that can not Medachange. For example, the KWG-type Rokusho's Parts are slightly more resistant than its successor's, Dorcus.
Prior to Medarot 3
Medachange was only seen with certain Medarots that would allow the player to move around. Landmotor and Landrotor, for instance, would help Hikaru and Ikki respectively to move around faster, and to achieve this, they would need to perform a Medachange and change from their Bipedal appearance (despite they are Vehicles) to a more car-like one. This was also seen in the manga and anime.
From Medarot 3 onwards
The first time it was ever seen in a game was in Medarot 3, to be later seen in Medarot 4 and by the last time in Medarot Navi. To perform a Medachange, the player must choose the below option, that, instead of having the Charge Medaforce option, it will have a big C icon, indicating it can Medachange (however, in Medarot Navi the player must press Select until the Drives option comes up, and when the player chooses to use a Drive the Medarot will Medachange). When the Medarot Medachanges, the new form will have its total armor equal to the sum of all of its Parts' armors, and its attacks changed to Drives.
When the Medarot changes back to its original form, the total damage done to its body will be shared equally to each Part.
Types of Medachange
There are two types of Medachange. One is known as the Shift Transform (シフト変形), and the other as the Power Transform (パワー変形). A Medarot's Medachange can only be of one of these types, and no Medarot has two Medachange forms.
A Shift Medachange is usually weaker than a Power Medachange, but it is a standard change. It has no backdraws and can be performed in any moment.
A Power Medachange is more powerful than a Shift Medachange, with the backdraw it manipulates Medaforce for every turn the Medarot keeps that form. In Medarot 3 and 4, it drains Medaforce, while in Medarot Navi the Medaforce can rise or fall.
The only Medarots shown to be able to Medachange were Landmotor and LadyJet.Landmotor could change from it´s bipedal appearance to a more car-like one, while LadyJet could Medachange from a bipedal form to a plane-like form.Despite granting Landmotor ease of mobility and LadyJet the ability to recover from a freefall while flying, it is unknown what other effects it might have done to them, and if its somehow similar or not to actual Medachange.
A similar effect is done to Giant Emperor, but it only changes him from multi-legged to bipedal.
In the anime, Medachange can only be done with Medarots and Death Medarots that have been designed to be able to Medachange. Medachange at this point is no different to the game canon, however the Shift and Power Medachanges don't exist. Instead, most Medarots and Death Medarots that can Medachange have been shown with two forms: Reckless Mode (レクリスモード, Action Mode in the occidental dub) and Crafty Mode (クラフティーモード, Demolition Mode in the occidental dub). A Medarot first must transform to its Reckless Mode. In this form the Medarot will gain a new type of legs, much like in the games, and new actions it can perform. However, it can't perform all three the Medarot could in the games. Instead, to perform the remaining ones, the Medarot must undergo a second change named the Crafty Mode, where new components will be transported to the Medarot in order to complete its transformation.
For example, Ikki's Metabee can shoot Missiles while it is in its Reckless Mode. However, to perform the other attacks it was supposed to be able to, Cross Attack Set and Cross Fire A, it must change to its Crafty Mode, where Metabee will charge a powerful shooting attack and then fire a huge energy ball.