Pokemon Emerald is an enhanced remake of Pokémon Ruby and Sapphire, adding to the third generation of Pokémon games. Like the games it was based on, the player controls a Pokémon trainer, whose general goal is to traverse around the Hoenn Region and capture Pokémon. Emerald features the Pokémon available in Hoenn, like Ruby and Sapphire, but also includes many Johto Pokémon once exclusive to Pokémon Colosseum and Pokémon XD: Gale of Darkness. The National Pokédex is also available without trading.
The story begins with a young player character moving to his or her new home in Littleroot Town. After spending time meeting the neighbors, including their child (who is May if the gamer chooses the male character for gameplay, or Brendan if the gamer selects the female character for gameplay) of Professor Birch, a renowned Pokémon researcher, the player hears a cry for help, and sees the Professor being attacked by a wild Zigzagoon. Taking control of one of his Pokémon, the player must drive off the Zigzagoon, receiving as a reward the Pokémon he/she used. Birch then sends his rescuer north to find his child, who challenges the player to a friendly practice battle. The two head back to Littleroot, where the protagonist decides to become a Pokémon Trainer, and sets out to visit his/her father, Norman, who happens to be the Gym Leader of Petalburg City. After Norman refuses to battle his inexperienced progeny, he sends his greenhorn child on a quest to defeat some of his weaker counterparts.
On the way, the player encounters Team Aqua, a crime syndicate bent on flooding the land to expand the ocean. Eventually the player meets Archie, the leader of said organization. Archie warns the protagonist not to interfere with Team Aqua’s plan. Travelling onward, the hero meets Team Magma, a parallel group that wishes to increase the landmass. Learning that Team Magma has stolen a meteorite, and is using it in an attempt to force dormant volcano Mt. Chimney to erupt, the player must team up with Archie. The two clash with Maxie, the head of Team Magma, and successfully prevent the volcano from awakening.
When the player encounters Team Aqua again, they are holding hostage a group of scientists that have supposedly learned how to control the weather. The battle is interrupted though, when they learn that Team Magma is racing to a Pokémon cemetery called Mt. Pyre in hopes of stealing a precious artifact held there, the Blue Orb. Delayed by Team Aqua, the player sees Archie stealing its counterpart, the Red Orb. One of Mt. Pyre’s caretakers entrusts the protagonist with the Magma Emblem, a medal engraved with Team Magma’s crest. Following Archie to the seaport of Slateport City, the player watches helplessly as he steals a prototype submarine. Back at Mt. Chimney, the Magma Emblem can be used to open the door to Team Magma’s hideout. Confronting Maxie, the hero learns of his plan to use the Blue Orb to reawaken Groudon, an ancient behemoth with the power to control heat and sunlight, and use Groudon’s powers to dry up the ocean. Although Maxie is defeated in battle, it is too late to stop Groudon from awakening. Unfortunately, the beast doesn’t respond to Maxie’s orders and disappears. Distraught, Maxie and his cohorts flee.
Heading to the seaside town of Lilycove, the protagonist spies a cave on the coast, which turns out to be Archie’s base of operations. Held up by constant attacks from Aqua grunts, he/she arrives too late, as Archie departs in his submarine. The player continues on to the Mossdeep City Space Center and obtains the power to Dive to the ocean floor. As he/she leaves, Team Magma invades the space center. The team plans to use the rocket fuel to ignite Mt. Chimney in a furious eruption; doing so will destroy their base and any evidence along with it. Defeated for a third time with the help of a local named Steven, Maxie realizes that his ideals were twisted, and he sets out to find Archie. Meanwhile, the player Dives down to a seafloor cavern, and finds a sleeping Pokémon, Kyogre, which has the power to create tidal waves and massive rainstorms. Archie arrives and reveals his plan to use Kyogre to flood the land. After the Red Orb awakes Kyogre, the leviathan departs, and Maxie arrives to inform the player and Archie that bizarre weather is affecting much of the surrounding area. Outside, the weather shifts between fierce rains and blazing heat, as Groudon and Kyogre resume the confrontation they started ages ago. If their battle continues, eventually the weather system of the whole world will be thrown out of balance.
At Sootopolis City, the battleground, Maxie and Archie try in vain to pacify the two legendary Pokémon. Learning of a third ancient Pokémon, Rayquaza, from a resident of the city named Wallace, the player heads to the Sky Pillar, Rayquaza’s home. Roused by the trainer’s presence, the giant dragon heads to Sootopolis and forces the two combatants back down, averting the disaster.
After the player defeats the Elite Four, they are able to encounter two Pokémon flying across Hoenn, Latias and Latios, and can access an area called the Battle Frontier, which adds several new challenges for the player. The player gains access to a battle with former champion Steven Stone in Meteor Falls, who uses a powered-up version of his team in Ruby and Sapphire. The player is now able to catch Kyogre and Groudon, which can be tracked by talking to the scientist in the Weather Institute.
While Emerald’s relation to Ruby and Sapphire is similar to that of Pokémon Yellow’s to Pokémon Red and Blue and Pokémon Crystal’s to Pokémon Gold and Silver, it also adds more dramatic changes and revamps than its two predecessors.
The Berry glitch that was in Ruby and Sapphire has been fixed. There are minor additions to Pokémon abilities. The abilities Keen Eye and Intimidate lower the proportion of low level wild Pokémon appearing, Hustle and Vital Spirit make high level wild Pokémon more common, Pressure and Arena Trap increase the amount of wild Pokémon that appear, Sticky Hold and Suction Cups increase the ability to catch Pokémon while fishing, etc. In the PC, moving capabilities have been added; players can now move Pokémon in large numbers, as well as give and remove items Pokémon are holding (before, players would have to withdraw the Pokémon to remove or give items). Wireless Adapter support (introduced in FireRed and LeafGreen) has been added. Double battles are now a lot more frequent as two separate people can team up against the player. A few areas that were empty of Pokémon Trainers have been reworked to include more Trainers. Pokémon have animations before battle, as in Pokémon Crystal. The Gyms’ layouts have changed, and the Pokémon of the Gym Leaders and members of the Elite Four have changed (this excludes Phoebe’s and Glacia’s teams). The game also has a Battle Tent in place of three of the Pokémon Contest Halls, each with a different Battle Frontier event. The Pokémon Contest Hall in Lilycove now contains all levels of Pokémon Contests. Pokémon Link Contests may be held with 2 to 4 players, but only if playing with other Emerald Game Paks. Playing with Ruby and Sapphire requires 4 players. The method of opening the caves to the three “Regi-” Pokémon (Regirock, Regice, and Registeel) is different. For Regirock, the player must go 2 steps left, then 2 steps down, and use Rock Smash. For Registeel, players must use Flash in the middle of his cave. For Regice, players bike, run or walk a lap around the room. Both Groudon and Kyogre can be caught; in Ruby and Sapphire, the legendary that appeared depended on who was on the cover of the game (Groudon could be caught in Ruby; Kyogre in Sapphire). However, both are now at Level 70 (they were at Level 45 in R/S). As a consequence of this, both Team Aqua and Team Magma are the protagonist’s enemies, and both of their hideouts can be entered. Team Magma now has a hideout in Jagged Pass that the character can access after obtaining the Magma Emblem in Mt. Pyre, while Team Aqua resides in the Seafloor Cavern and in the original base near Lilycove(this one is the official base of Team Aqua). Most of Wallace’s team has been altered, and he is the Pokémon League Champion, while Steven, the former Champion, is now in Meteor Falls, making his Pokémon stronger. The player can battle the Gym Leaders again after the Elite Four is defeated. All rematches are 2-on-2 fights and feature improved Pokémon teams, including some Kanto & Johto Pokémon. The Battle Frontier - a new way of battling. It takes the place of the Battle Tower in Pokémon Ruby and Sapphire. After the player beats the Elite Four, a new section opens up in the Safari Zone. In the new section, the player can catch Johto Pokémon. After completing the Hoenn Pokédex, the player can get one of the Johto starters (Chikorita, Cyndaquil or Totodile) from Professor Birch. Both of the desert fossils can now be collected. Players first find them in the Mirage Tower, which occasionally appears in the Mauville Desert (Route 111). At the top, there is the Root Fossil (becomes Lileep) and the Claw Fossil (becomes Anorith). The second fossil disappears after the other one is taken, but can be found and collected in a Ditto-infested cave called the Desert Underpass in Fallarbor Town after the player beats the Elite Four. Rayquaza can be caught after the cut scene between the three Legendary Pokémon at Sootopolis City. Both Groudon & Kyogre can be caught by going to the Weather Lab on Route 119 and talking to the scientist at the computer. If he says there is a drought on a route, there will be a cave with Groudon on that route. If he says there is a flood on a route, there will be an area one can dive in on that route with Kyorge inside. Mew can be caught on a special hidden island called Faraway Island using a special ticket given away at Nintendo events. Lugia and Ho-oh can be caught at Navel Rock using a special ticket given away at Nintendo events. Deoxys can be caught on Birth Island using a special ticket given away at Nintendo events. The player must choose between Latias and Latios. The other can be obtained on Southern Island if the player has the Eon Ticket. It must be obtained by mixing records with a Ruby/Sapphire game that has an Eon Ticket.
The Battle Frontier acts like a different region from Hoenn, and can be reached by beating the game. By defeating a stage, the player gets battle points which he or she can trade for items, Secret Base items or moves for Pokémon from Move Tutors. The several buildings in the Battle Frontier all represent different talents in which the player must have, for example the Battle Tower tests the players ability.