Codex

The Codex is an item almost unique to the Eder Region.

Origins
The Codex originated from scientists reverse engineering the Monolith and it's ability to affect the pokérus virus within Pokemon as well as its ability to stimulate Pokemon change over the years.

By buying z-stone material from alola and utilizing their special physical properties the scientists of the Eder Region were capable of simulating in their own laboratories smaller species specific monoliths by exposing the unprimed Codex to a pokemon with pokérus.

Mechanism
The codex utilizes the power of z-energy to power itself up by use of the properties of a z-stone, however by powering itself with z-energy originating from both Pokemon and trainer its original function becomes distorted from the Monolith.

As the monolith is responsible for collecting data, storing it, and then subtly altering the course of evolution whithin the pokemon species capable of reproducing into stronger forms the codex is capable of doing this too to pokemon it has been primed to, with much more effect.

The Codex collects all the pokérus associated with a given pokemon and alters it with the trainer's influence and the z-powers' influence and releases it back into the pokemon causing it to permanently change form.

Effects
For any of these effects to take place 252 EVs must be paid for the pokérus to alter the pokemon. As such its possible for a pokemon to suffer 2 different changes or utilize the changes twice.

However once the codex has been used once it becomes impossible to revert the changes.

Stat Changes
The most drastic ability a codex has is its ability to alter a pokemon's base stats. The codex can freely move around 100 stat points from any stat(s) into another(s), while keeping the stat total equal.

Furthermore pokemon with stats totals of below 600 are given extra stats for their efforts.


 * 500: +10
 * 400: +20
 * 300: +30
 * 200: +40
 * 100: +50

Using the stats changing effect twice no longer lets you move stats around but gives you an extra dose of free stats in the same pattern.

Ability Change
A very common utilization of the codex by trainers is changing their pokemon's ability to an hidden or an entirely different ability.

A pokemon can gain any ability from pokemon it is linked to genetically by egg group or elementally by their type.

However it's impossible for pokemon to gain signature moves as their genetic code is special for the pokérus virus and cannot be given freely.

Using the codex twice for abilities is pointless.

Move Changes
A rare and often overlooked aspect of the codex is its ability to have a pokemon learn moves from their types that they normally cannot.

Like with the ability change, signature moves seem to be completely missing and are thus impossible to be given to pokemon who don't naturally learn them.

Limitations and Drawbacks
As stated above the Codex cannot effect abilities and moves that are signature to any pokemon line.

Furthermore pokemon who have been altered by the codex have their EVs automatically reset and must be grown again from the start.