Pokemon Overlord

The Pokemon Overlords (Pokemon Rulers, or Emperors) are a group of Pokemon that only appear in Pokemon: Unlimited. They were first mentioned in Chapter 10, only with no actual context on them. According to info, they are Pokemon Explorers who are famously and infamously known around the world depending on their impact towards it. So far, there are only four well known Overlords in the world which are a Sceptile, an Aggron, a Pinsir and a Gardevoir.

Unlike a regular Pokemon Explorer, a Pokemon Overlord possesses tremendous power that can be equaled to that of Pokemon gods. Because of said power, it is one of the things that the Pokemon World Government wants to limit, fearing a repeat of history should they clash with one another.

Forming the Overlords
It was said that Francis Gatesworth, the strongest Pokemon in the world was considered to be an Overlord to which only few could rival with him. Some of the Overlords known in Happy's time were part of his crew, although they were more likely his crew mates. After his death, four of them went their own ways to form the great powers that would shake the world known as Pokemon Overlords.

Adam and Seth's Meeting
In Chapter 75, once Happy and his crew make it to the New Hope, Seth conducts a meeting with Adam, to which the Pokemon World Government overhears and feared what would happen if they clashed. As a response, they prepared the Military to deal with the situation in case things escalate. Although the pact between them was successful, the ending result was a clash that divided the very area itself over an argument that concerned Seth's condition and the murder of one of Adam's crew members by the Pokemon who was part of Adam's crew known as "Hypnotyst". While Seth was warning Adam of an upcoming future where a war would begin because of sending Cabbath to hunt Hypnotyst, Adam laughs it off and ends the conversation over his arrogance, forcing Seth and him to clash claws over. Afterwards, they never spoke to each other again.

On a remote island, Seth and his crew were brooding, with Seth himself appearing to be in a state of despair over his clash with Adam, causing a rainstorm from his mysterious powers. However, said rainstorm managed to fade away when Zorro appeared on the island and showed him a wanted poster of Happy, returning his smile once again. He then received a visit from a mysterious Pokemon who wanted to do "business" with him.