A player can reach Birth Island only after downloading the AuroraTicket through Mystery Gift and sailing there by talking to the sailor in front of the Seagallop Ferries in Pokémon FireRed and LeafGreen, or by boarding the S.S. Tidal in Pokémon Emerald.
Like Navel Rock, Birth Island is invisible on the Town MapFRLG by default due to its event-only status, only appearing when the player first arrives there. This is in contrast to the other Sevii Islands, which appear on the Town Map even before the player has visited them. It also never appears on the PokéNav's map.E
Upon first arriving at the island, the only thing the player will find is an inert, black, triangular rock. To make Deoxys appear, the player must solve a puzzle by following the rock: each time the rock is interacted with, it will move to a different position on the island, and the player must perform the shortest possible path to the rock's new position. Each successful interaction will cause the rock to glow more; the puzzle is solved once the rock returns to one space above its original position and glows a bright red. Interacting with the rock in this state will cause it to shatter and Deoxys to appear. If the player fails to follow the shortest path before the puzzle is solved, interacting with the rock will reset the puzzle, moving the rock back to its original position and reverting it to black.
A Deoxys appears here after solving the rock puzzle. If defeated, it respawns after entering the Hall of Fame. If run from, it respawns upon leaving the area.
This Deoxys is treated as having been met in a fateful encounter. This is not visible in the Generation III games, only becoming visible when transferred to a later generation; in Generation III, this flag is instead used to prevent Deoxys from disobeying the player and allows it to be traded.
Once captured, it will transform into its AttackFR/DefenseLG/SpeedE Forme.
Birth Island first appeared in Not Exactly Normal. After defeating Red on Five Island, the Deoxys known as Organism No. 2 retired to Birth Island in order to heal the damage it had received when Pika's Thunder struck its core. In order to protect itself, Organism No. 2 encased itself in a pyramid-like protection called "Delta Shield", a combination of Reflect and Light Screen. Giovanni, however, took advantage of Organism No. 2's weakened state, and followed it to the island in Going Green. Using his Beedrill's Agility to cut off its movements and his Aggron's Brick Break to destroy the Delta Shield, Giovanni was able to capture Organism No. 2 with a Poké Ball specifically designed to catch the DNA Pokémon.
In It's Starting to Make Sense Now, Sird revealed that Organism No. 2, which had been in incomplete at the time, had retreated to Birth Island after it had initially escaped from Team Rocket's captivity in order to fully complete its growth and awaken itself. When he had first learned this, Giovanni had mused that Birth Island was a perfect place for Deoxys to do such a thing.