Research: Emerald's Battle Frontier

[Agastya]

I've previously posted things involving Em's Frontier in the Quick Research thread, but it's been ages ago and they're buried under a bunch of posts. For quick reference the posts are here:

https://www.pokecommunity.com/posts/7092796/
https://www.pokecommunity.com/posts/7115858/
https://bulbapedia.bulbagarden.net/wiki/Battle_Frontier_data_structures_in_Generation_III (Not my work, but a great reference)
https://upokecenter.dreamhosters.com/games/emerald/guides/ (another great reference)


Anyway, since I've made these posts, I've cleaned up my notes into a simpler format. Since most everything related to the Pokemon it uses is known now, I figured it'd be best to get all of my notes in one publicly viewable place that actually has traffic in the hopes somebody else will be able to make use of them.

Battle Frontier, Slateport, Verdanturf, Fallarbor modules

Spoiler:

Offsets:
Battle Frontier: 0x5D97BC
Verdanturf Tent: 0x5DEC28
Slateport Tent: 0x5DE02C
Fallarbor Tent: 0x5DF69C

These follow a twelve byte data structure.

Species: 2 bytes
Movepool: 8 bytes (two per move)
Hold item: 1 byte (Determined by a master list located at 0x05CECB0)
EV spread: 1 byte
Nature: 1 byte
Padding/alignment: 1 byte

EV spreads are assigned by a bitfield to save space. Each stat with
EVs assigned to it will have the 510 EVs divided evenly among them.

HP: 0x1
ATK: 0x2
DEF: 0x4
SPD: 0x8
SATK: 0x10
SDEF: 0x20

Battle Pyramid wilds

Spoiler:

Offsets:
Lv. 50: 0x6126B0
Open Level: 0x612E80

The Battle Pyramid wilds follow a 12 byte data structure.

Species: 2 bytes
Levels: 1 byte
Unknown: 1 byte
Movepool: 8 bytes

In Level 50, the level byte is the Pokemon's base level when spawning.
In Open Level, the level byte appears to be how many levels below the
player they spawn at base. In both cases, the wilds have a few levels
in variance.

Frontier Brains

Spoiler:

Offset: 0x61156C

Frontier Brain Pokemon are stored in a 20 byte data structure.

Species: 2 bytes
Item: 2 bytes
IVs: 1 byte
Nature: 1 byte
HP EVs: 1 byte
Atk EVs: 1 byte
Def EVs: 1 byte
Spd EVs: 1 byte
Sp.Atk EVs: 1 byte
Sp.Def EVs: 1 byte
Moveset: 8 bytes

The item can be anything the hacker desires, following normal item
indexing instead of Frontier indexing.

All IVs are set to whatever the IV value is. Stick with a max of 31, I
haven't personally tried going higher.

EVs can go above 510 total. You can give something 255 EVs in every
stat and they all will be applied, but the game will lag a little bit
calculating the stats.

Each Brain's team is 120 bytes long. The first three entries are used
in their Silver symbol challenge, and the second three are for Gold.
Factory Head Noland's team data is two copis of Steven's team data at
the Mossdeep event since his team is randomly generated from the
master list as rental Pokemon.

Battle Pike wilds

Spoiler:

Offsets:
Spawn Table: 0x553934
Lv50 wild movesets: 0x6121D4
Open Level wild movesets: 0x612274

The Battle Pike wilds follow a 12 byte data structure.

Species: 2 bytes
"Level variance": 1 byte
Unknown (Padding?): 1 byte
Movepool: 8 bytes

The species byte itself does nothing but help categorize. Wilds have
to be edited in the wild encounter table itself. Each slot in the
moveset data is set to read a certain moveset, and the spawns are
shared between Level 50 and Open Level challenges.

The "level variance" field appears to be how many levels they spawn
below the player at base.

Lastly, here's sonic1's post on how to edit the Frontier's ban list, in case you wish to allow your players to rampage with Rayquaza or something.

In emerald, at the offset 0x611C9A, there's a table with 10 entries of 2 bytes (shorts), followed by an FFFF at the end of the table, which marks the pokemon restricted for entry in Battle Tower. To add or remove entries, add the pokemon number reversed in hex, and end the table with FFFF. If you want to remove all the limitations, just write FFFF to the beginning of the table (offset 611C9A).

~Sonic1

This is the main meat of the Frontier, anyway. There are other things that are worth looking into if you're planning on hacking the Frontier, and for the most part they're already indexed on the Bulbapedia page for Frontier structures.

After a while though, I got sick of doing everything in a hex editor. I came across the Nightmare Table Editor and realized that since Frontier stuff is all in tables, it could be used to make this easier so I made a few Nightmare modules to assist in doing so.

Nightmare is located here: https://datacrystal.romhacking.net/wiki/Nightmare_Table_Editor (apparently dead)
Nightmare 2 is located here: https://www.romhacking.net/utilities/610/ (no idea how well this will work)
And the modules are here: https://mediafire.com/?fb1hnme4hg7pc7e

Hopefully, somebody with better knowledge will be able to use these to make an actual proper tool for Frontier editing. I think it was planned to be a part of PGE, but for now it's not implemented so these have to do for the time being.

 

[Gamer2020]

Yes this will be part of PGE I've just been very busy. This research will certainly help when I get around to working on it. Good job.

 

[chaosakita]

Is there any way to change the banned pokemon in the battle frontier?

 

[Agastya]

yes but i unfortunately forgot where the offsets are

somebody else posted about them in the quick research thread, it'll be buried in there pagewise somewhere around where my first frontier post was

 

[DarkWolf13]

The Nightmare Table link is dead

 

[Agastya]

hm

well, there's nightmare 2 on romhacking.net but i have no experience with it

it also may not work happily since it's raw java

i'd rehost nightmare 1 but i'm not sure if i have clearance to do so

 

[Tigerfang98]

So how do you edit the frontier brain data? I don't understand. Could you post a tutorial or something?

 

[HoneClaw]

So how do you edit the frontier brain data? I don't understand. Could you post a tutorial or something?

It's not too hard. Just open up a hex editor, go the offset: 61156C. And then you should get the data for their teams. You can reference Bulbapedia for the 3rd Gen index numbers of Pokemon and compare them to the brain's team to figure out who they are.

For example, the first result you should see is 41 00 B3 00 18 0F 6A 00 98 98 64 00 09 00 07 00 08 00 32 00. This is Anabelle's Alakazam. After that you'll see her Entei (starts at F4) and then her Snorlax (starts at 8F). Agastya's list contains all you really need (although I am puzzled by that EV spread on Alakazam).

As long as you know the index numbers and such, it should be a piece of cake. Otherwise, there are probably good tutorials on here about hex editing, since I don't know of any editors for the Battle Frontier.


I guess the only thing I'm curious about is how it handles increasing the difficulty? There's always been accusations that the frontier "analyzes" your team, but it seems that it's solely based on win streak.

And for the Battle Arena, does adding extra moves break it? Since each move has a "mind" rating, how does it handle moves that are outside of the base 355?

EDIT: In the Battle Arena, moves past the regular index are treated normally, i.e. as 0 and nothing adverse happens to the game. Not that anyone will ever need to know this.

 

[Danny0317]

Is there any way to change the banned pokemon in the battle frontier?

https://www.pokecommunity.com/posts/7020447/ yeah that's the post.

Might wanna add that to the first post :)

Also, thanks a lot for this Agastya, this will surely be helpful :D

 

[Agastya]

replying in the quote because i'm too lazy to format - my replies will be in bold

I guess the only thing I'm curious about is how it handles increasing the difficulty? There's always been accusations that the frontier "analyzes" your team, but it seems that it's solely based on win streak.

enemy ivs increase with your winning streak, and pulls trainers that use 'more powerful' pokemon the longer the streak has been going on as well. each trainer has a list of pokemon it can use so they're mostly themed, and it makes sure to avoid breaking species clause. the frontier doesn't analyze your team outside of in the battle dome, where it runs a preset routine to decide what to use.

And for the Battle Arena, does adding extra moves break it? Since each move has a "mind" rating, how does it handle moves that are outside of the base 355?

EDIT: In the Battle Arena, moves past the regular index are treated normally, i.e. as 0 and nothing adverse happens to the game. Not that anyone will ever need to know this.

i believe you can just repoint the mind ratings list to go to a new location. but don't quote me on that, since i have no interest in expanding my own move table.

 

[apelhitam]

Hi Community members,

I'm new to the site and I was wondering if there is a way to edit the BF win streak record?

 

[Mister Coffee]

I'm still learning a lot of the basics of ROM Hacking, and I had a question related to this topic but not directly correlated with what you guys are conversing about in this thread.

I'm doing a project on a hack that uses Fire Red as it's host ROM, I wanted to eventually design a battle frontier within my hack that is more or less an exact copy of Emerald's Battle Frontier, I'm going to be changing a bunch of other stuff in the frontier so it will not be an exact copy, but I'm not concerned about that at the moment, what I'm worried about is will I have to completely build a new battle frontier from scratch in the Fire Red hosted ROM Hack, or could I somehow copy and paste all of the pre-built battle frontier information from the Emerald ROM into my Fire Red ROM?

Sorry if this question is a derailment. Thanks ahead of time.

 

[Agastya]

If you don't need to use FR as your base, then I would highly suggest switching to Emerald for your base or just living without a battle facility.

I don't doubt that you could port the Frontier to FR, but it seems like it would be more trouble than it's worth when you could simply just move on to an Emerald base and get all of Emerald's extra features as well.. but they probably pale in comparison to the freedom offered by the hacked engine, so I guess it's a moot point.

 

[Mister Coffee]

If you don't need to use FR as your base, then I would highly suggest switching to Emerald for your base or just living without a battle facility.

I don't doubt that you could port the Frontier to FR, but it seems like it would be more trouble than it's worth when you could simply just move on to an Emerald base and get all of Emerald's extra features as well.. but they probably pale in comparison to the freedom offered by the hacked engine, so I guess it's a moot point.

How complicated is it to write and edit the events and scripts that would produce a battle facility that is comparable to the battle facility within Emerald?
Not looking for any exact numbers, but a general idea would be helpful. Is it possible for me to just look at the scripted data within an Emerald ROM and just use the tools provided within the Fire Red ROM to recreate the battle facility? Is the amount of event and script information so large that it would take an incredible amount of time and care to replicate? Is there something about using the Fire Red ROM that would greatly hinder the progress of this kind of project, or is it simply that it is just an incredibly tedious task?
Thanks for the reply by the way and any future replies towards my questions.

 

[jToTheAvacola]

How complicated is it to write and edit the events and scripts that would produce a battle facility that is comparable to the battle facility within Emerald?
Not looking for any exact numbers, but a general idea would be helpful. Is it possible for me to just look at the scripted data within an Emerald ROM and just use the tools provided within the Fire Red ROM to recreate the battle facility? Is the amount of event and script information so large that it would take an incredible amount of time and care to replicate? Is there something about using the Fire Red ROM that would greatly hinder the progress of this kind of project, or is it simply that it is just an incredibly tedious task?
Thanks for the reply by the way and any future replies towards my questions.

I've been planning on porting the Frontier to FR for some time.

You can't simply copy and paste things from Emerald to FR. There's a lot of differences in commands and certain special commands that only exist in Emerald.

You'll have to learn how to insert ASM routines into your ROM if you haven't already. The Battle Pyramid and Battle Tower are pretty easy with the available resources.

The Factory and Arena would be really hard and I'd have no clue how to do them without FBI coming up with custom ASM for them.

The Pike can definitely be done with a lot of scripting. The Palace would be easier to recreate by changing the rules slightly and making it that pokemon just use random moves.

So yeah, I'd say the main problems are the Factory and Arena. I also had no idea how to recreate the tournament format of the Dome but I haven't looked at it super in-depth yet.

 

[Mister Coffee]

I've been planning on porting the Frontier to FR for some time.

You can't simply copy and paste things from Emerald to FR. There's a lot of differences in commands and certain special commands that only exist in Emerald.

You'll have to learn how to insert ASM routines into your ROM if you haven't already. The Battle Pyramid and Battle Tower are pretty easy with the available resources.

The Factory and Arena would be really hard and I'd have no clue how to do them without FBI coming up with custom ASM for them.

The Pike can definitely be done with a lot of scripting. The Palace would be easier to recreate by changing the rules slightly and making it that pokemon just use random moves.

So yeah, I'd say the main problems are the Factory and Arena. I also had no idea how to recreate the tournament format of the Dome but I haven't looked at it super in-depth yet.

Sounds Interesting. Seriously, I'm very interested.
I'm relatively new to ROM Hacking, I'm seriously just learning everything new and have been following a tutorial. However, I am doing a lot of experimenting with lots of different things and trying to learn more of the complicated features of making a ROM hack with large amounts of end game content, one of which was intended to be a battle frontier. However I had defaulted into messing around mostly with a Fire Red ROM. I will admit what I've done so far, it's not a ton of progress, so if I have to I'll just switch over to an Emerald ROM if that's really the only way.
However, although I'm fairly novice in all of this experience, I would still love to help you research the Battle Frontier in order to attempt recreating it within the Fire Red ROM, even if I don't use it for what I'm trying to build right now. If you point me in the right direction and don't mind a few noob questions here and there, I'm willing to help try to make sense of it.

 

[Agastya]

The Palace would be easier to recreate by changing the rules slightly and making it that pokemon just use random moves.

Then you're not in the Battle Palace, you're in the Battle Roulette.

Porting over the Frontier to FR isn't something that you can just do with the "good enough" mentality that seems to still persist here at times, it's either all or nothing in accuracy. I'm unsure as of why people are still adamantly against using Emerald for bases instead of Fire Red considering that we know how to do a lot more stuff in it and we know that the game isn't "unstable" but it really does need to come up in consideration more often.

 

[jToTheAvacola]

Sounds Interesting. Seriously, I'm very interested.
I'm relatively new to ROM Hacking, I'm seriously just learning everything new and have been following a tutorial. However, I am doing a lot of experimenting with lots of different things and trying to learn more of the complicated features of making a ROM hack with large amounts of end game content, one of which was intended to be a battle frontier. However I had defaulted into messing around mostly with a Fire Red ROM. I will admit what I've done so far, it's not a ton of progress, so if I have to I'll just switch over to an Emerald ROM if that's really the only way.
However, although I'm fairly novice in all of this experience, I would still love to help you research the Battle Frontier in order to attempt recreating it within the Fire Red ROM, even if I don't use it for what I'm trying to build right now. If you point me in the right direction and don't mind a few noob questions here and there, I'm willing to help try to make sense of it.

I'll answer any questions for you I can. I'm not a master hacker either but it will be very possible to port the entire Frontier if we really put forth the effort.

Then you're not in the Battle Palace, you're in the Battle Roulette.

Porting over the Frontier to FR isn't something that you can just do with the "good enough" mentality that seems to still persist here at times, it's either all or nothing in accuracy. I'm unsure as of why people are still adamantly against using Emerald for bases instead of Fire Red considering that we know how to do a lot more stuff in it and we know that the game isn't "unstable" but it really does need to come up in consideration more often.

Fair enough, but I don't think there would be much of a difference in gameplay experience. They might as well be using random moves. Regardless, even the real Palace is feasible, it would just be very annoying having to account for each individual move. Still it wouldn't be the one I'd be worried about.

 

[Agastya]

Pokemon do not use entirely random moves in the Battle Palace, and it is completely possible to build a strategy around it. For example, the Gentle nature has an 18% chance to attack, 70% chance to set up, and a 12% chance to use a status move when above 50% HP. When their HP drops, they will shoot up to a 90% chance to use an attacking move. You can raise a somewhat bulky Pokemon with a Gentle nature and give it a moveset that includes Swords Dance and a priority move and it will more often than not perform in a consistent manner (set up, then attack).

Another important factor is that the AI will not attack at all if they try to use a type of move that they don't have. In the situation you described, choosing random moves, the player can just put one or two powerful attacking moves on their Pokemon and call it a day with no punishment at all.

There is a difference in the gameplay experience, but only to users who would care enough to go for a win streak there. If you don't fully care about something, then you shouldn't implement it and disappoint the people that do care.