The Atari 2600 created the home console market in 1977 and is the reason cartridges exist. Pitfall!, Adventure and Space Invaders all started here, and its 128 bytes of RAM make it the least demanding system on this list by a wide margin.
Runs effortlessly on every R36 model. Many titles expect a single-button joystick, so the extra buttons go unused.
The chip is the same in every model, so the rating is too. What differs is the screen: 4:3 panels suit most home consoles, the 1:1 square panel suits Game Boy and GBA and shows 4:3 games with bars.
The R36 handheld family runs Atari 2600 titles with perfect compatibility out of the box.