The old Tamagotchi ones, yeah.
Speaking of which, those things had rigged hardware. I know because I had 5 of them and the different devices would always win in the same combinations regardless of how well or badly the Digimon on them were raised. My green one always beat my red one, lost to my gray one, and had exactly 50-50 odds against the other two. Red always beat yellow and gray, and lost all the time to the others... and I don't remember the rest.