Wii Remote
The Wii Remote is the Wii's primary controller. Many development revisions of it exist, and its development history is one of the most well-known parts of the Wii's overall development history, starting out as a project separate from the Wii itself.
Overall Development History
Nintendo begun experimenting with motion-based controllers in the late 1990s, including a watch-like controller for the Nintendo 64, however they did not ship any of these devices to third-party developers until 2000 when they shipped an early prototype motion controller to Factor 5, and possibly other development studio as well. When Nintendo finished development of the GameCube and decided to try the "blue ocean strategy" for their next console, the next console project was originally separate from the motion controller project, which was still planned to be a GameCube peripheral.
At this point, Nintendo contacted a third-party company known as Gyration to further develop the technology. Gyration had initially proposed their motion technology to Nintendo independently, and Nintendo was interested while Sony and Microsoft were not. As such, Gyration and Nintendo heavily collaborated on creating a variety of motion controller prototypes, with the original goal of being able to roughly preserve the GameCube's button layout. Gyration ultimately pitched the "GyroPod" concept to Nintendo, a break-away controller somewhat similar to the Nintendo Switch JoyCons. This concept was pitched in around 2003, and was ultimately developed into the Wii Remote as the new controller and new console projects merged.
By the end of 2004, the controller's wand shape and Nunchuk were finalized. Nintendo planned to demonstrate the controller at E3 2005, however these plans were scrapped.
Starting in around July of 2005, Nintendo began to ship these controller kits en masse to third-party developers. These kits were known as the "Dev Tool" series of controllers. 6 controllers were produced under this moniker; the Dev Tool v1, the Dev Tool v2, the Dev Tool v3, the Dev Tool v3.1, the Dev Tool v4, and the Dev Tool WB (WaveBird?). The Dev Tool v1 and 2 have not been seen, however from what little information is known about them they are presumably similar to the v3, other than connecting through GC memory card instead of the GC controller port. The Dev Tool v3 controller is the most well known of these, having been sold at a Japanese auction recently and having had its SDK libraries and documentation from the early late 2005 Revolution SDK leaked several years ago.