Yeah, I believe one of the Wario Land games was also a Game Boy/Game Boy Color hybrid.
It's definitely a weird specimen that I have no idea how to really explain and describe.
Pokemon Yellow seems to have a decent amount of color support compared to other original Game Boy games, such as Pikachu being in full color in the intro and title screen, but it was still packaged as an original Game Boy game.
There were also games like Hamtaro Ham Hams Unite, and Shantae, which got a few bonuses and minor tweeks when played on a GBA, but again, those were still just Game Boy Color games.
I guess in more modern times, the closest parallel I can think of is Hyrule Warriors Legends, where the game was clearly meant to be played on a N3DS, but can still be played on an standard 3DS, albeit with horrendous framerate.