tutorial [Tutorial][HGSS] Treat 2 different lines as the same species

[MeroMero]

Complete title: Treat two different lines as the same species for breeding purposes

Disclaimer: For now this goes for games in:

• English
  
• French
  
• German
  
• Spanish (SS only)
  

We already have the Nidos and Volbeat+Illumise.

This time we're going to add (not replace mind you) two new rules for breeding (males on the left, females on the right):

• the controversial Tauros+Miltank
  
• Gyarados+Milotic
  

• Decompress arm9.bin
  
• First we're going to change the pointer so that it points to the new piece of code, go to offset 0×6CA88 and change FFF7AEFE into 91F0F6FF
  
• At offset 0×FEA78 add this:
  

  F8 B5 84 B0 0D 1C 01 A9 00 90 6D F7 A1 FB 00 24
  01 AF A6 00 B8 59 05 21 00 22 6F F7 D5 FD 61 00
  03 AA 50 52 10 1C 40 5A 84 28 04 D1 01 20 60 40
  28 70 6C 70 08 E0 B8 59 71 F7 6E FA 01 28 03 D1
  01 20 2C 70 60 40 68 70 60 1C 00 04 04 0C 02 2C
  DF D3 28 78 41 00 03 A8 40 5A 72 F7 B3 FB 04 1C
  1D 2C 09 D1 00 98 2A F7 15 FC 02 21 89 03 08 42
  01 D0 20 24 00 E0 1D 24 F1 2C 09 D1 00 98 2A F7
  09 FC 02 21 89 03 08 42 01 D0 80 24 00 E0 F1 24
  1C 48 84 42 09 D1 00 98 2A F7 FC FB 02 21 89 03
  08 42 01 D0 81 24 00 E0 16 4C 13 48 84 42 09 D1
  00 98 2A F7 EF FB 02 21 89 03 08 42 01 D0 0F 4C
  00 E0 0D 4C 0E 48 84 42 00 D1 44 1E 68 78 41 00
  03 A8 40 5A 84 28 0B D1 28 78 81 00 01 A8 40 58
  71 F7 1A FA 01 28 03 D0 69 78 28 78 68 70 29 70
  20 1C 00 00 04 B0 F8 BD 3A 01 00 00 39 01 00 00
  EA 01 00 00 5D 01 00 00

  
  

This is it, or it is?

Not quite, remember that in gen IV if you try to breed male Nidoran / Volbeat with a Ditto the offspring will always be male.

This is because the code checks when the offspring is female Nidoran or Illumise, if it is the case then the egg has a 50 % of hatching into either the species of the female or the species of the male.

To fix this follow the following steps:

• Open your ROM in CrystalTile2
  
• Extract the folder poketool/personal/pms.narc: This is what the game use to tell the offspring that the a given species of Pokémon will produce.
  
• We're going to change the following:
  
  • 20 00 into 1D 00 (3 times)
    
  • 80 00 into F1 00 (once)
    
  • 81 00 into 5D 01 (twice)
    
  • 39 01 into 3A 01 (once)
    

Note: you can also give Tauros egg moves now.