Pokémon Emerald is the fifth Pokémon game of the advanced generation, after its predecessors Ruby, Sapphire, FireRed, and LeafGreen. It takes place in the world of Hoenn but can also connect with Kanto-based games FireRed and LeafGreen as well. Like Pikachu and Suicune were for Yellow and Crystal respectively, Rayquaza plays a vital role in this game along with the other Legendaries, Groudon and Kyogre. Though similar to the original storyline that occurs in Hoenn, Emerald offers more changes than Yellow and Crystal.
In terms of gameplay, there have been several alterations to the game:
Legendaries- Ability to catch Rayquaza before the Elite Four, as well as both Groudon and Kyogre after it.
- Changes to catching the Regis.
- Ability to catch either one of Latios or Latias.
Graphics- New outfits for the characters.
- New Pokémon animations.
Features- Ability to enter the Safari Zone Extension, where you can catch Johto (the world of Pokémon Gold, Silver and Crystal) Pokémon like Houndour and Miltank.
- The Battle Frontier, an island full of different battle stadiums.
- Ability to get both of the Claw and Root fossils.
These are of the changes you might notice at first while playing Pokémon Emerald. However, there are lots of other improvements apart from the new storyline that separates this game from its predecessors.