Original: PokÃ mon Emerald, a special edition version, was released two years later in each region. These three games (PokÃ mon Ruby, Sapphire, and Emerald) are part of the third generation of the PokÃ mon video game series, also known as the "advanced generation".
Simplified: PokÃ mon Ruby and Sapphire had a remake called PokÃ mon Emerald, which changed a few things, and added a Battle Frontier.