[Other] Trainer related help

[Sonikku A]

Hello! For my Emerald romhack, I want to have a specific trainer battle that does the following
-Use music unlike other battles. In my case, GSC route38 since I cheekily swapped the midi and voice bank ref with a custom one
-Have the opponent NOT throw the pokeball when summoning their Pokemon
-Custom text if player tries to throw a pokeball, separate from the regular one
What scripts would I need to edit to do so?

 

[WiserVisor]

-Use music unlike other battles. In my case, GSC route38 since I cheekily swapped the midi and voice bank ref with a custom one

I can answer this one. I can think of two ways you could go about this. They both have their benefits, and it all just comes down to which path you prefer.
Option 1: Special Music Via Trainer Name

Spoiler:

This option is more straight forward and is only limited by how many unique names you can come up with, but it requires you to add your character's name into a couple other files, as well as add some code to a method that is a bit inconsistent compared to the rest of the code within the method.

First, you need to make sure you have a unique name for the trainer in question. You'll want to make sure to add this name to a file within src as a const u8 array. I'd suggest putting it in src/battle_message.c, just because Wally's name is placed in there for the same reason. For example, if your character's name was "JOHNNY", you'd want to add this line into the file:

const u8 gText_BattleJohnnyName[] = _("JOHNNY");

You will then need to jump over to the correlating file within include, which in this case would be include/battle_message.h. In there, you would add:

extern const u8 gText_BattleJohnnyName[];

Once you have your trainer's name in there, hop over to src/pokemon.c. Look for

u16 GetBattleBGM(void)
{

Within this method, look for:

else if (gBattleTypeFlags & BATTLE_TYPE_TRAINER)
    {
        u8 trainerClass;

Let's assume that your song name is "MUS_BATTLE_UNIQUE". Right below "u8 trainerClass;", add this:

if (!StringCompare(gTrainers[gTrainerBattleOpponent_A].trainerName, gText_BattleJohnnyName))
        return MUS_BATTLE_UNIQUE;

With that code, the next time you fight your special trainer, your custom battle music will play instead of the standard trainer battle music.

Option 2: Special Music Via Trainer Class

Spoiler:

This method is more consistent with the code already existing in the game, but you either are limited by the amount of unused trainer classes, or you have to add more trainer classes yourself to go beyond the unused trainer classes.

First, you need to make sure that the trainer that is in this particular trainer battle has a unique trainer class. You would have to pick out an unused trainer class in include/constants/trainers.h and give your special trainer that class. Either that, or add in a new trainer class to this file. I'm not sure what complications may arise by adding a new trainer class to this list, so unless you've already used the two unused classes, I'd recommend just using the unused ones. You can assign the trainer class in src/data/trainers.h. Next, you'll need to look into src/pokemon.c. Look for

u16 GetBattleBGM(void)

There, you'll eventually see a line that looks like this:

switch (trainerClass)

You'll see several cases, each case being a particular trainer class. Look for this:

default:
     return MUS_BATTLE20;

Directly above "default:", add an additional case statement just like the ones above, but write your unique trainer class instead. Then, put a return statement underneath it, with whatever the name of your song is being the returned value. For example, say your trainer class is called "TRAINER_CLASS_UNIQUE", and your song is called "MUS_BATTLE_UNIQUE". The code you would add immediately above "deafult:" would look something like this:

case TRAINER_CLASS_UNIQUE:
            return MUS_BATTLE_UNIQUE;

With this in place, whenever you fight that particular trainer, your unique song will play instead of the standard trainer battle theme.

I hope this works out for you! Let me know if you find any errors or issues, and I'll try to point you in the right direction.