EggRobo did not originate from fanon, and more information can be found on their respective wiki(s). You may read more about it on the following wiki(s):

Eggrobo generations
2D art from Sonic 3 & Knuckles
Species Robot
Align Evil
Current Status Dead
Main Weapon(s) Gun
EggRobo is a character from the Sonic series. So far, it has made appearances in Sonic 3 & Knuckles, Sonic R, Sonic Adventure 2 and Sonic Generations.

Fanon Appearances

Crazy Party: Fort Defense

EggRobo makes an appearance in Crazy Party: Fort Defense as a member of the Eggman Fort.