Add a new type

This tutorial is for how to add new types for Pokemon or moves. As an example, we'll be adding the Dark type first introduced in Generation II.

Contents

1. Define a type constant

Gen I was before the Physical/Special split, so any types with an index number less than $14 are physical, and anything afterwards or equalivent to is special. Dark type was classified as a physical type in Gen II and III, so we'll include Dark type as Type $09.

Edit constants/type_constants.asm:

 ; Elemental types
 NORMAL   EQU $00
 FIGHTING EQU $01
 FLYING   EQU $02
 POISON   EQU $03
 GROUND   EQU $04
 ROCK     EQU $05
 BUG      EQU $07
 GHOST    EQU $08
+DARK     EQU $09
 FIRE     EQU $14
 WATER    EQU $15
 GRASS    EQU $16
 ELECTRIC EQU $17
 PSYCHIC  EQU $18
 ICE      EQU $19
 DRAGON   EQU $1A
  TYPES_END EQU const_value

2. Give the type a name.

Edit text/type_names.asm:

TypeNames:

	 dw .Normal
	 dw .Fighting
	 dw .Flying
	 dw .Poison
	 dw .Ground
	 dw .Rock
	 dw .Bird
	 dw .Bug
	 dw .Ghost

+        dw .Dark
-	 dw .Normal
	 dw .Normal
	 dw .Normal
	 dw .Normal
	 dw .Normal
	 dw .Normal
	 dw .Normal
	 dw .Normal
	 dw .Normal
	 dw .Normal
	 dw .Normal

	 dw .Fire
	 dw .Water
	 dw .Grass
	 dw .Electric
	 dw .Psychic
 	 dw .Ice
 	 dw .Dragon

 .Normal:   db "NORMAL@"
 .Fighting: db "FIGHTING@"
 .Flying:   db "FLYING@"
 .Poison:   db "POISON@"
 .Fire:     db "FIRE@"
 .Water:    db "WATER@"
 .Grass:    db "GRASS@"
 .Electric: db "ELECTRIC@"
 .Psychic:  db "PSYCHIC@"
 .Ice:      db "ICE@"
 .Ground:   db "GROUND@"
 .Rock:     db "ROCK@"
 .Bird:     db "BIRD@"
 .Bug:      db "BUG@"
 .Ghost:    db "GHOST@"
 .Dragon:   db "DRAGON@"
+.Dark:     db "DARK@"

3. List the type matchups.

Edit data/type_effects.asm:

 TypeEffects:
 ; format: attacking type, defending type, damage multiplier
 ; the multiplier is a (decimal) fixed-point number:
 ;     20 is ×2.0
 ;     05 is ×0.5
 ;     00 is ×0
         db WATER,FIRE,20
	 db FIRE,GRASS,20
         ...
        db ICE,DRAGON,20
	db DRAGON,DRAGON,20
+       db DARK,GHOST,20
+       db DARK,PSYCHIC,20
+       db DARK,DARK,05
+       db DARK,FIGHTING,05
+       db GHOST,DARK,05
+       db BUG,DARK,20
+       db FIGHTING,DARK,20
+       db PSYCHIC,DARK,00
        db $ff

WIP