The E102-like robots that appear in Sonic Adventure 2/SA2 Battle are a modified version of Gamma, the E-1000 series robots. While they do look like Gamma, they're a modified version of it, and are actually enemey robots. They can be found in some of the desert Action Stages(Pyramid Cave, Death Chamber & Egg Quarters). Characters passing through usually encounter them at one point or another in those levels.
~Ron Prower & SA Tails