Nintendo 3DS – Is Trading Possible in the Digital Version of Pokemon Gold?

So, here's what I've managed to find out on my own:

1- With the Transfer Pak connected, there is another section added to the Pokemon Selection screen when you are preparing a Free Battle, which allows you to enter and register a team from your Gameboy Color game (it grants instant access to every legal option in your party and all of your boxes).

2- As mentioned above, you can register a team from your Gameboy Color game. This allows you to plug in your game, register your team, turn the N64 off, plug in your friend's game, register their team, and so on, allowing multiple people to play with their Gameboy Color teams without requiring multiple Transfer Paks at once. However, from what I can tell, you can only register teams for games using Preset Rules; if you're using a Custom Ruleset, you cannot register a team.

You have to close the eShop and keep the system on the HOME Menu, but other than that, there really isn't anything else to it - it just needs an Internet connection.

However, note that the eShop can sometimes be extremely slow to download from. You may be in for quite a wait; I've once waited about an hour for one of the demos to download.

If all of them continue to stay stuck at 0%, try canceling them and queueing them up again. You might also want to just download them directly from the eShop, without using Sleep Mode; this seems to occasionally work a little better.