I was looking into the obscure FE6 version of this password and only realized this thread is a thing now, so I wanted to post my findings since it seems most of the discussion is about FE7 currently. I want to make a video showing everything in action soon, but I wanted to write this out first for documentation.
Despite what Serenes mentions, I don’t think that FE7’s website ever ended up hosting such a contest, but FE6’s website definitely had one and still has the results up today (though unlinked from the main page). The contest took place for about a month after FE6’s release with 900 participants, and you can see their numerical stats for rankings. Unfortunately part of it ran on Flash Player which is not very usable now, but the individual ranks are still there in text form, and myself from 4 years ago discovering the website was able to note that it apparently mentioned the best stats in each ranking (with Power/Levels being graded by who had the lowest).
Pegasusknight.com mentions this contest existing too, but lists the FE7 Select method on the FE6 section which doesn’t work. People commenting on the website noted the password was a bit hard to input, which was my only lead of proof that there was such a password code publicly available at some point. I imagine it must have mentioned the input code at the time of the contest, but the earliest archive now is from December 2002 and I could not find any other sources from the time that may have noted it down.
Ultimately with some amateur reverse engineering and much guidance from community resources, I figured out you can access the password screen in FE6 on the final ranking screen by pressing Left Left Right Right L L Start. You have 20 frames to input each button which is pretty lenient.
Thanks to ghidra I found a few other uses of the function that checks for this input. If you perform the same input while hovering over a team in the Link Arena though, you get an even huger password with Japanese characters. I imagine this must contain all the stats of your characters, but don’t think this was ever officially used for anything either. This input is still recognized all the way through FE7J/FE7U/FE8J/FE8U but it no longer shows a password, it just fades to black and comes back to the same menu.
I also mentioned in the XMAP thread (XMAP Chapters [FE6] - #2 by Flame) that this also enables trial map transfers (from Player 1) if done from the main menu of the link arena, which was really neat.
Notes:
The function that handles the inputs to activate these screens is at 0x8036D60. It takes an address argument that contains the inputs to compare to.
The proc (I think) that handles inputs on the ranking screen (pressing A or B to leave normally) is at 0x808F22C. It calls a function at 0x8036DEC, which just calls the input function with address 0x85C9A18. This contains the 7 inputs in bitflag form. The link arena long password version uses 0x85C9A08 while the XMAP transfer uses 0x85C99F8, but they all represent the same input anyway.
I want to thank and credit these resources: Function Library by MisakaMikoto for pointing out where PrintPassword is located in FE6 which was a big lead, StanHash’s FE6 decompilation for reference points, and FEBuilderGBA/mGBA/ghidra for ultimately figuring things out and debugging how everything works. I don’t really have much experience in this field, but these resources from the community made it pretty accessible to get started on a whim and find some closure to this mystery.