Everybody has just said what I wanted to say...
If ever I was to summarized Pokemon:C/G/S it would be:
"The first to take the game to a whole new level." and here's why.
Pokemon was the rave for most kids a decade ago. And I'm proudly one of them. Now, if you was that kind of kid you'd know that Pokemon:Red/Blue was very addictive. Until Gold/Silver and later Crystal came along. I'd never knew as a kid how great the changes in this games are until now. Its classical gaming innovation at its finest. I'm not trying to make it sound grand but there's a reason why I'm calling it a great innovation.
C/G/S doesn't stray far from the gaming formula of Blue and Red but what makes it more enjoyable was the whole new features in it.
First and what I would say the most notable feature is the 24/7 cycle found in the game. Yes, the game has an internal clock. You can set the time and day and runs parallel in real life too. Plus there's night and day version of each locale. Pokemon and people you may encounter differ on what time of day you're in. All the DS version of the game has this too and it's a testament of how C/G/S created a path for this games to follow.
Second was the daycare center. It's a matter of convenience. Never mind if you had found out that pokemon hatches in eggs but being able to make multiple Eeves was a blessing. 6 more was listed in the pokedex.
Third was the whole new region and pokemons. One of the game's purpose is to collect...err..catch them all and there are 100 new pokemons including 5 memorable legendaries and the final 251th one. As a pokemon nut, man, it was awesome even if I'd never collected them all.
Last but not the least was the story's progression. You start as a new adventurer in the world of Pokemon but there are recurring characters from R/B. Johto and Kanto shares the same Pokemon League venue but there are new members in the Elite Four. Team Rocket also returns. And after becoming the champion you'll be able to visit the first game's region Kanto. Two regions in one game. It was that cool. And 16 badges. 16 BADGES. SIXTEEN badges. And being able to battle Red was the most defining moment for me.
All in all, this is gaming's classics. Played this two years ago and I still found this mildly enjoyable. Plus the cartridge works not only in GBC but also in GBA. Now, if only I could find that damn cartridge. I know it's here somewhere.