The original Pokémon Red and Blue are available in 3DS from early 2016. In the original game, you must purchase a title specifically designed for each language. However, in 3DS, you can just purchase a language-agnostic copy and choose whatever language you like on the game.
So I wonder how you can pick up your preferred language in the game. Also, what languages are available to begin with? I'm not sure which language was available in the original version, but I know Chinese was not available as it has only been added since Sun and Moon.