itch.io

I think the easiest way to add this would be having a new global array of "mega evolutions data" which has three items per row: base monster, mega monster, and held item needed for the transformation.

• When generating the Moves menu, check each row of the mega evolutions data and if both the base monster and held item matches this monster's data, add a fifth option for mega evolution (unless you've already mega'd another monster in this battle, which you'd keep track of in a separate variable), picking this option will change that monster's species to the mega monster.

• All mega IDs should be at the very end of the monster data, perhaps even beyond MONSTER_MAX so the data won't e.g. get added to the dex.

• At the end of battle, go through the mega evolutions array again and if any of the player's party monster has a mega species, change it back to the regular species.