[Tutorial] Lunos' Wonder Trade System

[Lunos]

Hi.
In the past few days, I've been working on a Wonder Trade script after seeing the one that the user Harlee Quinn came up with.
Since it has some pretty nasty flaws and it can't be used in serious projects, I've decided to share it.
So without further ado, let's do this.

For this tutorial we'll need:
-A Pokémon Fire Red (USA) v1.0 ROM or a Pokémon Emerald (USA) ROM.
-A GBA Emulator
-Whichever text and hex editors you prefer to use.
-HackMew's Assembler which you can find right here
-HackMew's "Take Pokémon" ASM Routine which you can find right here
-Advance Map and XSE, obviously.

Instructions:
1) Compile the "Take Pokémon" Routine made by HackMew which I linked up there.
Use the Fire Red or the Emerald version depending on which ROM you're modifying.
Here's a video showing the process.

Here's the compiled routines for those who are lazy:
Fire Red:

Spoiler:

FF B5 00 25 11 4E 0F 4F 3C 78 02 2C 18 DB 33 88 A3 42 15 D2 62 1E 3A 70 01 33 E2 1A 64 25 6A 43 52 08 6B 43 08 4F F8 18 41 1B 0B DF 6C 43 3F 19 7F 1B 00 20 19 22 01 25 01 C7 01 3A 00 2A FB D1 35 82 FF BD 29 40 02 02 84 42 02 02 C0 70 03 02

Emerald:

Spoiler:

FF B5 00 25 11 4E 0F 4F 3C 78 02 2C 18 DB 33 88 A3 42 15 D2 62 1E 3A 70 01 33 E2 1A 64 25 6A 43 52 08 6B 43 08 4F F8 18 41 1B 0B DF 6C 43 3F 19 7F 1B 00 20 19 22 01 25 01 C7 01 3A 00 2A FB D1 35 82 FF BD E9 44 02 02 EC 44 02 02 E0 75 03 02

Then paste the compiled routine in an offset with at least 50 bytes of free space.
You can search one using Free Space Finder or your Hex Editor itself (lots of FF Bytes = Free Space).
Since I like to play things safe, I also suggest you to use an offset that ends in 0, 4, 8 o C. I've put it the Routine for Fire Red in 71A250 and the one for Emerald in E3CF80.

2) Go to Advance Map, choose a map and add a NPC on it with the following script, again, depending on which ROM you're modifying
Fire Red:

Spoiler:

#dynamic 0x71BBA0
#org  @start
faceplayer
lockall
msgbox @String1 0x5
compare 0x800D 0x1
if 0x1 goto @snippet1
msgbox @String2 0x6
releaseall
end

#org @snippet1
countpokemon
compare LASTRESULT 0x1
if 0x1 goto @snippet7
msgbox @String3 0x6
special 0x9F
waitstate
special2 0x8003 0x147
compare 0x8003 0x19c
if 0x1 goto @snippet8
compare 0x8004 0x6
if 0x4 goto @snippet3
goto @snippet4

#org @snippet3
msgbox @String2 0x6
releaseall
end

#org @snippet4
random 0x19C
compare 0x800D 0x0
if 0x1 goto @snippet4
compare 0x800D 0xFB
if 0x3 goto @snippet5
compare 0x800D 0x115
if 0x4 goto @snippet5
goto @snippet4

#org @snippet5
copyvar 0x8000 0x800D
bufferpokemon 0x0 0x8000
showpokepic 0x8000 0xA 0x3
waitcry
callasm 0x8FFFFFF+1
givepokemon 0x8000 0x5 0x0 0x0 0x0 0x0
pause 0x13
fanfare 0x13E
msgbox @String5 0x4
waitfanfare
closeonkeypress
hidepokepic
msgbox @String6 0x5
compare 0x800D 0x1
if 0x1 call @snippet6
msgbox @String2 0x6
releaseall
end

#org @snippet6
countpokemon
subvar 0x800D 0x1
copyvar 0x8004 0x800D
fadescreen 0x1
special 0x9E
waitstate
return

#org @snippet7
msgbox @String7 0x6
releaseall
end

#org @snippet8
msgbox @String8 0x6
releaseall
end

#org @String1
= Wanna wonder trade?

#org @String2
= Come back anytime.

#org @String3
= Select the Pokémon you wanna trade.

#org @String5
= [player] got a [buffer1]!

#org @String6
= Wanna give it a nickname?

#org @String7
= Sorry, you need two Pokémon\nto use the Wonder Trade.\pCome back anytime.

#org @String8
= I'm sorry, you cannot trade\na Pokémon Egg using the\lWonder Trade System.\pCome back anytime.

Emerald:

Spoiler:

#freespace 0xFF
#dynamic 0x71BBA0

#org  @start
faceplayer
lockall
msgbox @String1 0x5
compare 0x800D 0x1
if 0x1 goto @snippet1
msgbox @String2 0x6
releaseall
end

#org @snippet1
countpokemon
compare LASTRESULT 0x1
if 0x1 goto @snippet7
msgbox @String3 0x6
special 0xA2
waitstate
special2 0x8003 0x149
compare 0x8003 0x19c
if 0x1 goto @snippet8
compare 0x8004 0x6
if 0x4 goto @snippet3
goto @snippet4

#org @snippet3
msgbox @String2 0x6
releaseall
end

#org @snippet4
random 0x19C
compare 0x800D 0x0
if 0x1 goto @snippet4
compare 0x800D 0xFB
if 0x3 goto @snippet5
compare 0x800D 0x115
if 0x4 goto @snippet5
goto @snippet4

#org @snippet5
copyvar 0x8000 0x800D
bufferpokemon 0x0 0x8000
cry 0x8000 0x0
showpokepic 0x8000 0xA 0x3
waitcry
callasm 0x8FFFFFF+1
givepokemon 0x8000 0x5 0x0 0x0 0x0 0x0
pause 0x13
fanfare 0x13E
msgbox @String5 0x4
waitfanfare
closeonkeypress
hidepokepic
msgbox @String6 0x5
compare 0x800D 0x1
if 0x1 call @snippet6
msgbox @String2 0x6
releaseall
end

#org @snippet6
countpokemon
subvar 0x800D 0x1
copyvar 0x8004 0x800D
fadescreen 0x1
special 0xA1
waitstate
return

#org @Snippet7
msgbox @String7 0x6
releaseall
end

#org @snippet8
msgbox @String8 0x6
releaseall
end

#org @String1
= Wanna wonder trade?

#org @String2
= Come back anytime.

#org @String3
= Select the Pokémon you wanna trade.

#org @String5
= [player] got a [buffer1]!

#org @String6
= Wanna give it a nickname?

#org @String7
= Sorry, you need two Pokémon\nto use the Wonder Trade.\pCome back anytime.

#org @String8
= I'm sorry, you cannot trade\na Pokémon Egg using the\lWonder Trade System.\pCome back anytime.

Note: FFFFFF+1 = Offset where you've put HackMew's Routine, +1.
As I said before I dropped it in 71A250, which means that I'll have to use "callasm 0x871A251".
In the case of Emerald I've put it in E3CF80, that means that I'll have to use "callasm 0x8E3CF81".

3) Test.

Credits
-Harlee Quinn, because her/his script inspired me to make this.
-Bela, because he told me how to check if the Player decides to cancel the special 0x9F by using the B Button.
-HackMew for all the contributions that she has made to the Pokémon ROM Hacking Community.
-Dani_SR_17 from Wahack for his suggestion to optimize the filter in #org @snippet4.
-BluRose for helping me to understand an incredibly stupid mistake that I was having while implementing said filter.
-Anonymous tester from Pokémon Shiny Gold Sigma for noticing that Eggs were tradable.
-LuHo for creating Advance Map.

Here's a quick video showcasing the result in Fire Red.


Here's a quick video showcasing the result in Emerald.


And that's it.