I'm not super familiar with 3ds/2ds emulation, can you tell me what emulator you're using and link me a page where I can read more about it? If it's particularly accurate emulation I'll consider allowing it. Generally it's discouraged to use unofficial translation patches though. That said, even if it's not valid for leaderboards it's a fine way to practice starting off, and once you learn the few menu movements you need to remember it's not too bad to play with Japanese.

First of all I don't think a category should be made until a run exists at the very least, and then if there's enough interest go from there.

As for getting to the beast from a fresh file, you'd be looking at (as far as I can remember) a mom kill, 10 heart kills, 3 Hush kills, and one Mother kill before you even unlock the ascent. You also wouldn't have any characters unlocked by default, a lot of items would be locked, including stuff like knife, Dr. fetus, tech.5 and death's touch, and Isaac wouldn't start with the D6. That's about 15 half runs you'd have to complete first, with a severely gimped file compared with a fully unlocked one. It wouldn't even be unbearably long (I'd estimate maybe 2.5-3 hours...?), it'd just be annoying I feel, just a load of busywork before you can actually get your beast kill. I don't imagine it's a category that would be super popular.

Might try it myself later just to see what it's actually like but I don't imagine it'd become a category many people actually want to grind.

We need SDBL and Gaiden.

I've yet to see any real time runs of either of those games. Gaiden especially seems like RNG hell, and combined with its long length (even the TAS is like 2 hours iirc, and that's with manipulating 1/500ish enemy drops and perfect luck elsewhere) I think getting a good real time run is unlikely.

FE1 seems more reasonable though, especially with the anniversary release upcoming, which could get some attention with it's speed up functions (it'd have to be a separate category to NES runs though obviously). There are also a few cool glitches which could make it a somewhat interesting watch. The game is still very slow though, but a lot less RNG heavy than gaiden at least.

I noticed that, for the book 2 leaderboards, both of the submitted any% runs went for the good ending, in which, after collecting all the star shards and spheres, defeating Hardin unlocks the final few chapters of the game. In FE6, any% and all chapters are split into different categories, and in FE12 the only submitted run is submitted under all chapters rather than any%, since it goes for the good ending too. I'm just wondering if there's any particular reason that in FE3, all chapters is considered the "any%" here, when that feels incorrect, and also inconsistent with the series as a whole.