Pokémon Ruby and Sapphire/Tickets

Southern Island
Eon Ticket is a ticket obtained via an E-reader card. It was given away several times at special Nintendo events. The other legendary bird (Latios or Latias) is found using this card. On Southern Island you find the other one. To get there, use the ticket on the S.S. Tidal. Once there, go to the center to encounter the legendary. The legendary will also be holding a sacred item, the Soul Dew, which will raise the Special Attack and Special Defense of Latios and Latias.

Faraway Island
Unfortunately, this island is only available on Emerald, and this is the site where Mew appears. To get there you need an Old Sea Map, obtained from a special Nintendo Event. By catching it and trading it, Mew becomes available on Ruby and Sapphire.

Birth Island
Unfortunately, this island is only available on Emerald, FireRed, and LeafGreen. This is the site where Deoxys appears. To get there, you need an Aurora Ticket, obtained from a special Nintendo Event. By catching it and trading it, Deoxys becomes available on Ruby and Sapphire.

Naval Rock
Unfortunately, this island is only available on Emerald, FireRed, and LeafGreen. This is the site where Ho-oh and Lugia appear. To get there, you need a Mystic Ticket, obtained from a special Nintendo Event. By catching it and trading it, Ho-oh and Lugia become available on Ruby and Sapphire.