You have to beat one of the games, in order to get a password that links the games together. (This is either the Labrynna secret or the Holodrum secret, depending on the game you start with). This is called Main Linking, and allows you access to different content, along with "secrets" from characters, which are passwords you can take back to the original ...
The 3DS doesn't have any actual link between the two games, it's still just using the password system, to transfer back and forth your new items (sword and shield upgrades, the biggoron sword etc). Just remember that the passwords are generated on your specific game, based on where you are at in the story, what items you have, what you named Bopin and his ...
The password is based on several factors.
Your character name.
What you name the child in town.
What animal partner you pick.
Your progression in the game (including game completetion tag on/off)
What items you have unlocked.
As far as the exact algorithm, that I have no clue about.
The 3DS version is the original GameBoy Color version (so it's missing the Advanced Shop, but you can edit your saves to add in the exclusive rings).
All of the colouring tweaks found in the Advance version are also missing.
GBA with the Advance shop open on the left. 3DS Virtual Console version on the right.
There is almost no practical purpose for the Octo Ring. It's supposed to be just a fun ring which serves no useful purpose. However, the ring does grant immunity to being captured by Like-Likes while it is in use (source). Save the space in your ring box for more useful rings.
Unfortunately, there is no game in which Farore holds a role as important as Din or Nayru in the Oracle games. Well, kind of. She was meant to appear in Mystical Seed of Courage along with Oracle of Ages and Oracle of Seasons, but the game was cancelled due to the complexity of having to synchronize 3 games.
As a result of having her own game cancelled, ...
There was supposed to be a third game featuring Farore, but Capcom decided that it would be too complex to link three games together. Instead, Farore cameos in both Oracle games in the Hall of Secrets as the Oracle of Secrets, where she is responsible for allowing the player to enter passwords that link the two games together.
There has been no word from on ...
Because the 3DS lacks any sort of capability to use the Game Link cable, the only way you could connect your old games to the new 3DS ones is by using the password system. The 3DS version seems to accept passwords and secrets the same way the original games did, so you should be able to input them with no problem, as the games are direct ports from the old ...
They can be flipped using either the shovel (with some timing) or the gale seeds also work
Additionally, (though not quite on-topic), you can use the like-like ring which can be obtained in Gasha seeds, mini-games or Maple meetings, to transform into a like-like, thus becoming impervious to being eaten and having your items stolen.
This article seems to offer a clear guide through the lost woods, as far as I can remember.
The first path to take is that which leads to the L-2 Sword. Link needs to start by changing the season to Winter in the current, first screen. Head left once and change the season to Autumn, then left again and change the season to Spring. Continue left another ...
From various posts found on GameFAQs (example, another example), I think you can assume that the Advance Shop is unfortunately missing in both Oracle of Ages and Oracle of Seasons.
I did not find any official source yet, but there is a sufficient amount of people on the internet complaining about it to be sure that they are missing.
After doing some research, there is no hard evidence that the game was specifcally released on separate cartridges for the Game Boy (GB), Game Boy Colour (GBC, and the Game Boy Advance (GBA), though I can provide some insight.
Firstly, the OOA and OOS games were produced for the GBC, with additionally functionality, should it be played on the GBA (emphasis ...
OK. So, the sword was in my inventory the whole time. (Apparently, it was given to me somewhere near the start of the game. Maybe I missed the mention of the sword somewhere in the spew of dialogue?)
In any case, the sword was not actually equipped, even though it is clearly the only thing that could possibly be equipped.
Maybe this was my own simple ...
Ben is right about what you can use to defeat the spiked beetles.
You can also use a Gale Seed to go back to the dungeon once you've been there (there's a seed tree right below it). No need to go through the forest again.