Pokémon: Emerald Version (JP) is the enhanced remake of Pokémon Ruby and Pokémon Sapphire. This makes Emerald part of the third-generation of Pokémon games. The game follows a slightly modified storyline from Ruby and Sapphire. This time, both Team Aqua and Team Magma are serving as villains, and you are able to catch both Groudon and Kyogre. The main story Pokémon in this game is Rayquaza, which is featured on the front of the cover.
Emerald adds many new elements, such as the Battle Frontier, where the player can enter Pokémon battles with other trainers. It also adds the ability to receive a Johto starter Pokémon (Chikorita, Totodile, or Cyndaquil) after completing the Hoenn Pokédex. Talking about the Pokédex, there is now a new thing called the Pokénav which has a map of Hoenn, and tells if people want to have a rematch against you. In addition, the Pokémon of the gym leaders and Elite Four have been changed, the Elite Four has a new Champion, you can battle past gym leaders again, and Johto Pokémon have been added, as well as the usual graphical upgrades. Unlike the previous games that have been third (Pokémon Yellow and Pokémon Crystal), it has been said that a lot of new content has been added to Emerald, and it is not just a way of "milking" the Pokémon franchise.
Pokémon Emerald was 2005’s second best-selling game in the United States, and was the best selling Game Boy Advance game in the U.S.