What are the requirements needed to access Faraway/Birth Island in Emerald/FRLG?

Question

Some guy on Reddit is asking this:

I'm getting ready to hunt Deoxys across four Gen 3 games (FR/LG/E x2), as well as Mew in a Japanese copy of Emerald. Is there a certain point in each game's story that I need to reach before I'm able to obtain the Key Items and go to Faraway/Birth Island?

I figured in Emerald you need access to Slateport but because I'm not an expert on Hoenn and know nothing about the Sevii Islands, I have no idea what the answer to his question is. Assume they have access to legitimate events via e-Reader or whatever, (again, not an expert.)

Answer 1

Firstly (and most obviously) you need the S.S. Ticket that takes you between Lilycove, Slateport and Batle Frontier. This is given to you by Norman after you beat the Elite Four.
Secondly (and second obviously) you need the tickets required to get Deoxys and Mew. These are the AuroraTicket and the OldSeaMap respectively. To get this, you needed to attend events long time ago. The latter specifically was only released in Japan and Taiwan (meaning any Mew caught on Faraway Island on any other copy would be flagged as illegal)
However, here comes the hard bit. The game does an internal flag check which triggers the 'The ferry for SLATEPORT is...' dialogue which takes you to the event islands.
These flags are only marked when you actually get the tickets through the Mystery Gift system and the green man on the second/first floor of the Pokemon Centre (another flag of its own)
Unlike the Eon Tickets, as far as I am aware, you cannot transfer the tickets from another save file to this one through Record Mixing, and if you somehow cheat the tickets in, the flags will not be checked.
Unless the person finds a way to get to the islands, either through legitimate or illegitimate methods, those are the requirements as far as I am aware of.

EDIT 11/05/2024: I’ve got some new information about the flags relating to the event triggers. How to change the flags so that it triggers? I dunno.

The AuroraTicket flags in Emerald:
0x13A - FLAG_GOT_AURORA_TICKET
0x1AD - FLAG_FOUGHT_DEOXYS
0x8D5 - FLAG_ENABLE_SHIP_BIRTH_ISLAND

Comments

Where's your sources? Why would you need the SS ticket to go to other places that aren't included in the SS Ticket? I also said assume they have the event items

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Also when is the earliest in the game you can use the event exclusive tickets? I think this doesn't completely answer the question.

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@MonkeyBusiness If you try and get the ferry without the SS Ticket, you will notice that the ferry is not there. “The ferry service is not available at present” will be shown.
@sumwun After you beat the Elite 4 and get the SS Ticket.