Nintendo

 Nintendo is currently a publishing company that publishes many series', including the Super Mario series, The Legend of Zelda series, the Kirby series, and the Metroid series and manufactures consoles such as the Wii and the DS(as well as the DSi, DSi XL, 3DS, 3DS XL). Their mascot is none other than Sonic's rival, Mario.

Console Wars
Nintendo and Sega's rivalry ignited with the fourth console war, where the Nintendo Entertainment System (or NES for short) was competing against the Sega Master System. Nintendo and Sega's rivalry expanded to to four different wars. Nintendo and Sega were certainly not alone. During these wars, there were other systems. These include:
 * NES vs. Master System (third generation)
 * SNES vs. Sega Genesis (fourth generation)
 * Nintendo 64 vs. Sega Saturn (fifth generation)
 * Nintendo GameCube vs. Sega Dreamcast (sixth generation)
 * TurboGrafx-16 (16-bit; fourth generation)
 * PlayStation (32-bit; fifth generation)
 * Xbox (sixth generation)
 * PlayStation 2 (sixth generation)

Final War
During the sixth generation, the Dreamcast did so poorly, that it lost to the the PS2 and never competed against the Xbox. The Dreamcast was then discontinued.

Third-party company
Sega's next move was announcing that they would not be making consoles anymore, and become a third-party company. Since then, Sega has worked with Nintendo to create many Sonic games on Nintendo systems, including Sonic Advance for the Game Boy Advance, and Sonic and the Secret Rings for the Wii.

Crossovers
Sega and Nintendo started working to create crossover games between their mascots, Mario and Sonic. The first game was Mario & Sonic at the Olympic Games for the Wii which featured Mario, Luigi, Peach, Daisy, Bowser, Wario, Waluigi, and Yoshi for Team Mario, and Sonic, Tails, Knuckles, Amy, Blaze, Shadow, Vector, and Dr. Eggman for Team Sonic. The popular release caused the recent demand for Sonic to be in Super Smash Bros. Brawl to grow, and later on, he was confirmed to be in SSBB, which was also for the Wii. One year later, Sega released Mario and Sonic at the Olympic Winter Games which, again, was for the Wii, which included all the previous characters, with the addition of two new characters for each team: Bowser Jr. and Donkey Kong for Team Mario, and Metal Sonic, and Silver for Team Sonic. Then in 2011, Sega and Nintendo released Mario and Sonic at the 2012 London Olympic games which, AGAIN, was for the Wii, and had the same characters as Mario and Sonic at the Olympic Winter games. Sonic will probobly return in SSB4, which is planned to be on the Wii U and Nintendo 3DS.

Home

 * Color TV Game
 * Nintendo Entertainment System
 * Super Nintendo Entertainment System
 * Virtual Boy
 * Nintendo 64
 * Nintendo GameCube
 * Nintendo Wii
 * Nintendo Wii U

Handheld

 * Game & Watch
 * Game Boy
 * Game Boy Play-It-Loud!
 * Game Boy Pocket
 * Game Boy Light
 * Game Boy Color
 * Game Boy Advance/Game Boy Advance SP/Game Boy Micro
 * Nintendo DS/DS Lite/DSi/DSi XL
 * Nintendo 3DS/3DS XL

Trivia

 * Nintendo has a magazine called Nintendo Power, which notably provided the first looks at Sonic and the Secret Rings, Sonic and the Black Knight, Sonic Colors, and Sonic Generations (3DS).
 * Nintendo's and SEGA's logos are both the color of their respective mascots, Mario and Sonic.