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Mega Evolution

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Charizard and Venusaur using Mega Evolution (animated image)

Mega Evolution is a system introduced in Pokémon X and Y to enhance some Pokémon by temporarily boosting their stats and other features during battle. In Essentials, these changes are treated as a specialised kind of form change.

See also

Multiple forms

  • Mega Evolutions are treated as form changes.

How Mega Evolution works

Mega Evolution can occur when the player possesses a Mega Ring, and when a Pokémon is holding a particular item. If these conditions are met, then the option to Mega Evolve that Pokémon will appear in the Fight menu when choosing a move for that Pokémon to use. Only one Pokémon per trainer can Mega Evolve in a given battle.

The Mega Evolution is an extra part of a battle round, and a Pokémon can both Mega Evolve and use a move in the same round. The Pokémon remains Mega Evolved until the end of the current battle, regardless of whether it switches out or faints. Its held item (the Mega Stone) is not consumed by this process.

Mega Ring (Depending on the version)

In Essentials v15 and below, the Mega Ring is not an item. It is a switch, like the Pokédex and Pokégear are. To give the player a Mega Ring, use the following code:


You can set this to false to take it away from them.

You may also want to give the player a key item which represents the Mega Ring at the same time. However, bear in mind that this item will do nothing by itself.


In Essentials v16+, the Mega Ring is an item. Although it is not in Essentials you can add it (Or a varient) by adding the following lines to the text document "Items" in the PBS folder. Give the player the item and you will be able to mega evolve your pokemon

596,MEGARING,Mega Ring,Mega Rings,8,0,"(What ever description you want)",0,0,6
597,MEGABRACELET,Mega Bracelet,Mega Bracelets,8,0,"(What ever description you want)",0,0,6
598,MEGACUFF,Mega Cuff,Mega Cuffs,8,0,"(What ever description you want)",0,0,6
599,MEGACHARM,Mega Charm,Mega Charms,8,0,"(What ever description you want)",0,0,6

If you want to make your own mega item, you will follow the same process you would to create a new item, just change the name to "Mega Necklace", "Mega Glove", etc. Next, you'll need to go to "PokeBattle_Battle". Lines 650-657 define the variants of the Mega Ring. Line 652 will read:

if pbBelongsToPlayer?(battlerIndex)


Simply add on the name of your desired Mega Item, create an event in which an NPC gives you the item, make sure you have a Pokemon that can mega evolve, and their mega stone (which has to be held by said Pokemon), and you're ready to mega evolve your Pokemon with your new item.

Mega Stones

A Mega Stone is an item to be held by a Pokémon. It has no effect of its own, although the form of the Pokémon holding it can depend on it being held.

Mega Stones should be unlosable if they could cause the holder to Mega Evolve. That is, the holder should not be able to lose their held Mega Stone via Knock Off, Switcheroo or by any other means. Search the scripts for the name of a Mega Stone which has already been implemented in Essentials (e.g. VENUSAURITE) and copy how it works for any new Mega Stones you want to implement.

Preventing Mega Evolution

In the script section Settings, the value NO_MEGA_EVOLUTION is defined (34 by default). If the Global Switch of this number is on, then no Pokémon is able to Mega Evolve, not even if they otherwise could. This applies to both the player and enemy trainers alike.

Performing a Mega Evolution

Choosing to Mega Evolve a Pokémon is done at the same time as choosing a move for it to use. Any computer-controlled trainers will always try to Mega Evolve their Pokémon.

There are several examples in Essentials of how to define a Mega Evolution for a species. The following code is found at the bottom of the script section PokemonMultipleForms:

   next 1 if isConst?(pokemon.item,PBItems,:VENUSAURITE)
   next 0
   next _INTL("Mega Venusaur") if pokemon.form==1
   next [80,100,123,80,122,120] if pokemon.form==1
   next getID(PBAbilities,:THICKFAT) if pokemon.form==1
   next 24 if pokemon.form==1
   next 1555 if pokemon.form==1

The first three procedures ("getMegaForm", "getUnmegaForm" and "getMegaName") are unique to Mega Evolution.

  • "getMegaForm" decides which form is the Mega form for that species. If this produces a number, it can Mega Evolve. If it simply does "next", or if this procedure doesn't exist for a species, it cannot.
  • "getUnmegaForm" is the opposite of the first procedure, and produces the base form to revert any Mega Evolved Pokémon back to.
  • "getMegaName" produces the name of the Mega Evolution. If this procedure simply does "next" or it doesn't exist, then the name will simply be "Mega" followed by the species name.

The rest of the procedures are normal form differences, as can be used by any Pokémon with multiple forms. There is nothing special about these - the only special part is deciding whether a species can Mega Evolve, and if so, into which form.

There is also an example in Essentials of how to define a species with multiple Mega Evolutions (Charizard).

What is seen in battle

When a Pokémon Mega Evolves, a few messages are shown stating what happens. A Common animation called "MegaEvolution" is also shown.

Setting up an enemy trainer for Mega Evolution

Main article: Defining a trainer

The only thing enemy trainers need to perform a Mega Evolution is for one of their Pokémon to be holding a Mega Stone. They do not need a Mega Ring. As mentioned above, the AI will always make an enemy trainer's Pokémon Mega Evolve if it possibly can. Enemy trainers are still limited to one Mega Evolution per battle, though.

Giving an enemy trainer's Pokémon a Mega Stone to hold is the same thing as giving it any other item to hold.

Sprites, icons and cries

Main article: Multiple forms

Mega Evolutions are a kind of alternate form. Therefore their form-specific sprites, icons and cries are defined and named just like any other form-specific resource file.


  • You can expand on the number of species which can Mega Evolve.
    • Be wary about letting Pokémon with multiple forms Mega Evolve. You may need to change some effects in order to make them work properly.

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