Soaring with Steven
In Pokémon Omega Ruby and Alpha Sapphire, the island is visited as part of the storyline. While the player is talking to Steven on the east side of Route 118, LatiasOR/LatiosAS appears before the two, asking for their help to protect its counterpart. The player and Steven ride the Eon Pokémon, soaring to Southern Island. Steven will offer to return the player to Route 118 if talked to, where he will wait for the player to return. He will not let the player go further along Route 118, but he does allow them to return to Mauville City, and can be talked to on Route 118 to return the player to Southern Island if this offer is accepted.
At Southern Island, the player encounters CourtneyOR/MattAS and a Team Magma GruntOR/Team Aqua GruntAS, who battle the player in a Multi Battle.
After the player defeats the villainous team members, LatiosOR/LatiasAS joins the player's party, holding its respective Mega Stone (if the player's party is full, they must send one of their party Pokémon to the PC). Noticing the Mega Stone, Steven also gives the player a Mega Bracelet. Their mission completed, the two Trainers return to Route 118. The island cannot be accessed again unless the player has an Eon Ticket.
If the player's storage and party are both full either before traveling to Southern Island or before entering the inner grove, they will be prevented from advancing until they make space.
Eon Ticket e-card that was distributed in Nintendo Power volume 173
If the player has the Eon Ticket, they can travel to Southern Island. In Pokémon Ruby, Sapphire, and Emerald, this is the only way to access Southern Island; in Pokémon Omega Ruby and Alpha Sapphire, the player cannot visit Southern Island again without the Eon Ticket after defeating the villainous team members here.
In Pokémon Ruby, Sapphire, and Emerald, the player must first receive the Eon Ticket from Norman. With the Eon Ticket in the Bag, the player must then attempt to board the S.S. Tidal from the Lilycove City Harbor. A Sailor will replace the usual guide, taking the player to Southern Island. In the center of the island's forest there is a mysterious sphere; upon interacting with it, the player will be attacked by a wild Latias or Latios (whichever did not roam Hoenn).
In Pokémon Omega Ruby and Alpha Sapphire, the player must first receive the Eon Ticket from the deliveryperson in a Pokémon Center. If the player talks to Norman in the Petalburg Gym after obtaining the Mega Bracelet, he escorts the player to the Slateport Harbor. A Sailor will replace the usual guide, taking the player to Southern Island. This sailor will offer to return the player to Slateport if talked to, although the player actually goes straight back to the Petalburg Gym if this offer is accepted. At the back of the island's forest is LatiasOR/LatiosAS, who will battle the player if interacted with. This Pokémon is not holding its Mega Stone, unlike its partner. After catching it, they player will immediately find a Soul Dew on the ground and put it in their Bag; if the battle ends with the Pokémon not being caught, it will remain staring at the player.
In Pokémon Ruby and Sapphire, the player cannot return to Southern Island after battling this Pokémon even if defeated. In Pokémon Emerald, the player can freely return to the island regardless of the battle's outcome. In Pokémon Omega Ruby and Alpha Sapphire, if the player battles the Pokémon but does not catch it, it will remain and can be battled again; however, after catching it and leaving the island, they cannot return.
Obtaining the Eon Ticket
In Pokémon Ruby and Sapphire, to obtain the Eon Ticket the player must either connect their game to an e-Reader and scan the physical Eon Ticket and then talk to Norman who gives the ticket, or mix records with a player who has done so. In Pokémon Emerald, to obtain the Eon Ticket the player must mix records with a Pokémon Ruby or Sapphire game that has been connected to an e-Reader that has scanned an Eon Ticket card.
In Pokémon Omega Ruby and Alpha Sapphire, the player must either obtain one with a code via Mystery Gift, or StreetPass someone who already has the Eon Ticket.