item-newbox | Incorrect skipping of parameters in evolve.asm

[MarioBones]

There are a few spots in engine/pokemon/evolve.asm where hl is incremented the wrong number of times and so the Pokemon's evolutions are not checked properly. This is only really noticeable on Eevee and Tyrogue but any Pokemon using EVOLVE_HAPPINESS or EVOLVE_STAT can theoretically encounter the issue.

If you step through EvolveAfterBattle_MasterLoop.loop when Eevee levels up you can see incorrect and invalid values for evolution methods get passed into a:

The following changes need to be made in evolve.asm:

; EVOLVE_STAT
	call GetNextEvoAttackByte
	ld c, a
	ld a, [wTempMonLevel]
	cp c
-	jp c, .skip_evolution_species_parameter
+	jp c, .skip_half_species_parameter

	call IsMonHoldingEverstone
-	jp z, .skip_evolution_species_parameter
+	jp c, .skip_evolution_species

...

.happiness
	ld a, [wTempMonHappiness]
	cp HAPPINESS_TO_EVOLVE
-	jp c, .skip_evolution_species_parameter
+	jp c, .skip_half_species_parameter

...

; TR_NITE
	ld a, [wTimeOfDay]
	cp NITE_F
-	jp nz, .skip_half_species_parameter
+	jp nz, .skip_evolution_species
	jp .proceed

.happiness_daylight
	ld a, [wTimeOfDay]
	cp NITE_F
-	jp z, .skip_half_species_parameter
+	jp z, .skip_evolution_species
	jp .proceed

I haven't done any testing with trades so it's possible that there's issues with EVOLVE_TRADE that I'm not aware of.

[Rangi42]

I think a good solution would just be making all evolutions three values: dbww method byte, 16-bit param, 16-bit species. The param could be an item ID, move ID, etc, or some combination of two bytes for more complex methods (e.g. dbbbw EVOLVE_STAT, 20, ATK_LT_DEF, HITMONCHAN or dbbbw EVOLVE_LEVEL, 35, IN_GALAR, GALARIAN_WEEZING).