These games are the first Generation II games. They were originally released for Game Boy Color in 1999 in Japan and in 2000 in the West. While the original games were also compatible with the Game Boy, on the Virtual Console they will run like they did on the Game Boy Color.
The Virtual Console releases will be compatible with Pokémon Bank, which will allow the Pokémon to be transferred to Pokémon Ultra Sun and Pokémon Ultra Moon.
The Virtual Console releases will support communication via 3DS local wireless communications. They can communicate with other Virtual Console copies of Pokémon Gold and Silver, but can also use the Time Capsule function to communicate with Virtual Console versions of Pokémon Red, Blue and Yellow.
Pokémon Crystal was not mentioned in the announcement. It does not appear that it will be released on Nintendo 3DS Virtual Console at this time.
No Virtual Console release has been announced for South Korea. The Generation I Virtual Console games were not released in South Korea either.