Terastal energy

Terastal energy (Japanese: テラスタルエネルギー Terastal energy) is a type of energy in the Pokémon world derived from the Tera Pokémon, Terapagos. This energy was researched by Professor Sada^S/Professor Turo^V during their stay in Area Zero. This energy can cause Pokémon to Terastallize, either naturally or through the use of Tera Orbs, a device created by the professor.

The Terastal symbol as it appears in Pokémon Mezastar

In the core series games

Pokémon Scarlet and Violet

After a series of seismic shifts that took place over two million years ago in the Paldea region, Terapagos became nearly extinct. One specimen survived and became trapped in what is known in the present day as the Area Zero Underdepths. It slumbered there for millennia in the form of a large gem. As time went on, Terastal energy began to spread from Terapagos throughout the Great Crater of Paldea, eventually turning into crystals and crystallized structures, including a large tree within the Underdepths. Special herbs with healing and growth powers, known as Herba Mystica, also began to grow in Area Zero. At some point, Glimmet and Glimmora started appearing in the crater, feeding on Terastal energy seeping through the walls of Area Zero's caverns.

Over time, explorers and researches traveled to Area Zero in attempts to uncover its secrets. Legends were told of "precious stones", "wondrous fruits", and some manner of valuable treasure. Over 200 years prior to the events of Pokémon Scarlet and Violet, the Area Zero Expedition team, which included the historian Heath, claimed to have reached the depths of Area Zero. Heath described his experiences in the Scarlet Book^S/Violet Book^V including the discovery of Herba Mystica and an apparent encounter with Terapagos in its Stellar Form. 60 years later, Terastal energy began affecting the Pokémon within Area Zero, giving rise to the Terastal phenomenon in which a Pokémon becomes crystallized, their moves are strengthened, and even their typing is changed.

10 years prior to the events of the games, Professor Sada^S/Professor Turo^V, inspired by Heath's writings, began researching Area Zero with the goal of bringing Pokémon from other timelines to the present. Their research into Terapagos and its energy led to the naming of Terastal energy and Terastallization itself. The professor used their research to create the Tera Orbs, allowing Pokémon to Terastallize outside of Area Zero, which secured funding for further research. The professor eventually used Terastal energy to create an AI-powered robot with their exact appearance and the two succeeded in creating a time machine to summon Pokémon from the ancient past^S/distant future^V.

Today, many Paldean Trainers, Gym Leaders, Elite Four members, and Champions use Tera Orbs to Terastallize their Pokémon during battles. Pokémon also began to naturally Terastallize outside of Area Zero, either in the wild or in Tera Raid Battles.

The Teal Mask

Hundreds of years ago in Kitakami, Ogerpon and its human companion travelled all the way there, the man had with him some Tera Crystals from a foreign land. Later on, Kitakami's mask-maker used these crystals to craft four masks for the pair so they can blend in with the other villagers of Kitakami. These crystals on the masks are the reason Ogerpon possesses its Terastallized states and why it is capable of Terastallizing without the use of a Tera Orb.

At some point, somehow, at the top of Oni Mountain, the Crystal Pool was formed on it, a natural lake with many Tera Crystals on its bottom; it's possible one of the Tera Crystals Ogerpon's companion possessed fell into the lake, creating the Crystal Pool, but that's unproven. Legends in Kitakami say that the spirits of the dead can be seen around the pool.

The Indigo Disk

In the Unova region's Blueberry Academy, Briar created the Terarium Core to fill the whole Terarium with Terastal energy, so Terastallization is possible. She achieved this by filling the core with a mixture of Paldea soil and water from the Crystal Pool in Kitakami. Following the events of the story, she tries adding crystals from the Area Zero Underdepths to the mixture, causing the Pokémon in the Terarium to not only Terastallize but also Terastallize with the rare Stellar type.

In Area Zero Underdepths, the Tera Crystals found in Area Zero and Crystal Pool are shown to be much larger and Briar refers to some of them as pure Terastal energy, which blocks their way to find Terapagos. The only way to pass through them, is by taking down wild Pokémon Terastallized with the Stellar Type. During the final battle against Stellar Form Terapagos, the depths were so filled with Terastal Energy, that a Pokémon could be Terastallized several times while Terapagos absorbed it to try and stop the player from beating it. Following these events, the player's Tera Orb (as well as those belonging to Carmine and Kieran) will be overcharged with Terastral energy, no longer requiring them to be recharged between battles.

Later on, if the player goes to Kitakami's Crystal Pool carrying with them, Terapagos and Briar's Book, Terapagos will come out of its Poké Ball and use its powers and the Tera Crystals in Crystal Pool to bring the real Professor Sada^S/Professor Turo^V from either the past or another timeline, implying this is how "spirits of the dead" are seen around the pool.

Trivia

The origin of this energy is similar to the origins of Z-Power and Galar particles.