DKII on 13 December 2008
GB/GBC were kind of vague originally since when GBC launched most games worked on both systems. The cartridges were the same and the only real difference between the two was color. It's like halfway between a hardware revision and a new system. DSi may end up in a similar situation someday.
That said, there's not a single PS2 game that can be played on the PS1, or a single PS3 game that can be played on the PS2, and so on, so your comparison there is rather dumb.
Game Boy Micro, Pocket, etc. are equivalent to PS2slim and DSLite and are lumped together for obvious reasons.
