It is true for Sonic 1, but Sonic 2 is infamously difficult on Game Gear, because the levels where designed with the Master System in mind, and it didn't port w

It is true for Sonic 1, but Sonic 2 is infamously difficult on Game Gear, because the levels where designed with the Master System in mind, and it didn't port well to the smaller Game Gear resolution (160x144 vs 256x192): the assets are the same size, so the effect is almost like a truncated viewport.