>>11772590
Red & Blue are the same game but differing versions, and I think that the only differences are which kind of Pokémon you can find in the wild, some will be available in both, others can only be found in one or the other.
This was to encourage trading, and thus also battling, the end goal being to catch all 150 Pokémon by trading with your friends (some Pokémon will only evolve if you trade them). You didn't really get anything special out of completing your Pokédex except for bragging rights, however.
Later generations made this increasingly daunting by introducing more and more Pokémon, and then also making some only evolve or become available at all through sometimes needlessly convoluted and tedious methods (GameFreak can get fucked for those goddamn "Feebass tiles").
Yellow was a special edition, and it had some tweaks and additions to it to make it more like the anime which was very popular at the time. This would be things such as having what's supposed to be the Pikachu from the show as your starter (you being Ash Ketchum and all), him following you physically in the game world, special interactions with him, as well as adding in Jesse & James.
I forget if Yellow had the Pokémon availability setup of Red or Blue, or if it had its own distinct one.
