Do the stat exp to evs tutorial then make CheckShininess in engine/gfx/color.asm use the pokemon's OT ID XOR personality bytes. Then change every instance of CheckShininess in code.
[EDIT] CheckShininess in engine/battle/core.asm:BattleCheckShininess
Do the stat exp to evs tutorial then make CheckShininess in engine/gfx/color.asm use the pokemon's OT ID XOR personality bytes. Then change every instance of CheckShininess in code.
[EDIT] CheckShininess in engine/battle/core.asm:BattleCheckShininess