Mona
"Mona" is the self-chosen name of the True Form. In truth, while the entity with this ability is a Giratina, Mona is not classified as one. It is an unknown, eldritch dragon that feeds on the wishes and desires of others. It lurks through the shadows and travels from world to world to prey on unsuspecting creatures, granting the creature the tools and ability to do or have anything that it desires for a significant amount of time. The greater the desire, the more she feeds onto it. Then, after the dragon has her fill, Mona abandons the creature without warning, leaving them to sink into despair as the creature now must deal with the consequences of its actions. The more the creature relied on her for desire and the greater the desires granted, the deeper the abandoned creature would fall into despair.
As for Mona's appearance, the dragon is indescribable. Whenever it approaches its prey, it stays in the shadows and never shows its true figure or its true voice. Mona is incomprehensible to the average person. Looking at her true figure will cause any human, Pokémon, and even minor Legendary Pokémon to break and lose their sanity. As such, Mona only shows her true face in rare circumstances.
Mona used to freely roam the multiverse; however, she was banished after falling victim to her own desire abilities.
Mona and Giratina
Mona has the ability to assimilate other Giratina with their consent. Upon assimilation, the Giratina retains their personality and, most of the time, all of their memories. Mona's Distortion World is then linked to that Giratina's Distortion World, allowing the Giratina to travel from its Distortion World to her directly. If an assimilated Giratina dies, then it will wake up and return to its Distortion World, meaning that it effectively has an infinite amount of lives; however should Mona die in their Distortion World, then ALL assimilated Giratina also die. This is known as a "True Death".
If two Giratina meet that are assimilated with Mona, they are compelled to perform an "Assimilation and Combat Exchange". This is a full-out fight between the two Giratina. During this fight, the two Giratina exchange knowledge and memories so they may better know and understand each other. This is important in order for the two individuals to become friendly to each other. During the exchange, if one Giratina attempts to summon the True Form, the summoning will fail on either end.
Mona gives each assimilated Giratina their own respective special Griseous Core. This Griseous Core allows the Giratina to use some of her power, allowing them increased power and even change appearance. In addition, Mona is able to see through the eyes of the Giratina with the Core, obtaining its memories in real time. Giratina and Mona can also communicate and coordinate directly. Mona is able to take complete control of a Giratina's actions and speech; however, typically, this is done voluntarily.
The Presence
Mona communicates through its presence. The presence often speaks to an individual narratively and not through traditional spoken words; however, it can speak normally on occasion. No matter how it speaks, text is written in purple text to symbolize that it is either directly or indirectly speaking. When in Mona's direct presence, it can sometimes feel like a perpetual chill crawling down your spine.
Sometimes, an assimilated Giratina may speak of Mona. When that occurs, there is the chance that some of the words that Giratina says that refers to the presence turns purple. This is the presence assisting Giratina in its descriptions in real time, and only really happens in a Mona-infested Distortion World. In addition, when in a Mona-influenced Distortion World, some text that directly refers to said world will turn purple as well.