As an aside, I do not remember Game Boy lasting 25 hours on 4 AA batteries. They were 4-6 hours AT BEST for me, and I played on it quite a lot. But maybe my memory is hazy.
The Gameboy Pocket certainly had the shortest battery life of the GB/Pocket/Color trio due to using 2 AAA batteries. My experience with the original is that the batteries last a long time.