For the Xbox 360, the only concern is having the disk based expansions. There are three disks involved here:
  • Original Xbox 360 disk with FFXI + CoP/RotZ/ToaU
  • Xbox 360 expansion disk with WotG.
  • Xbox 360 Ultimate Collection disk with FFXI + CoP/RotZ/ToaU/WotG

As you can see, you don't need a special disk for AMK, ASA, ACP, or any of the Abyssea expansions, since those were all downloaded content.

When Seekers of Adoulin comes out, you'll have to get a disk for that as well. Hopefully SE releases that disk with all the expansions on it to make things easier for players.

Quote Originally Posted by Ire View Post
So my question here is, Can you get a registration code for a new account?
The cheapest and easiest way to get a code for an account that includes all the expansion packs and add-on content is to buy the Ultimate Collection - Abyssea Edition online. Many places sell it and will often have sales, such as directly from Square Enix's website, or from the popular distribution service Steam. The game with every expansion ever made costs $20 when not on sale and also comes with a code for a free hat.

You do not want to buy the game any other way - otherwise buying each expansion pack and add-on costs about $10 each, meaning you'd be paying somewhere to the tune of over $100 for what you can get for $20 or less, and you wouldn't get the hat. If you do get a working game code otherwise, buying the game and applying the game code to your account will unlock all the expansions for you as well, also making it the cheapest way to get codes.

Codes work dependently of platform, meaning that it doesn't matter if you've only ever played on the PC all the time, you could log into an Xbox with your PC account right now, or even a PS2. Keep in mind that when you log into an Xbox you have to link your account to a gamertag (which needs to be registered for the free version of Xbox Live in order to play), which will forever be linked, so if you want achievements from a particular account on a particular gamertag, be sure to link them wisely.