After Pokemon Scarlet and Violet only got two trailers in the span of five months, The Pokemon Company finally released a third one via the Pokemon Presents on August 1. The third trailer was more expansive than previous ones, being three-minutes long with a follow-up world overview for Gen 9 that delved deeper into some spicy new features for Pokemon Scarlet and Violet. One of the most anticipated pieces of information was what kind of battle gimmick Gen 9 would have, and if it would reprise Mega Evolutions - one of the most beloved features in the series.
The main gimmick for Pokemon Scarlet and Violet was revealed to be something else entirely called Terastallization. What Terastallization does is empower a single Pokemon per battle for the duration of the encounter by changing its original typing to a set Tera type, reportedly coming with a STAB Tera move that all creatures in Paldea can learn. Every Pokemon in the region is eligible for Terastallization, and every Pokemon has access to every type in the game for its Tera type if fans are willing to search them out. So far, The Pokemon Company showed five out of 18 Tera-type symbols, leaving 13 to be revealed in the future.
Bug
The already revealed Tera-type symbols include a chandelier with lit candles for Fire-types, flowers for Grass-types, a fountain for Water-types, colored balloons for Flying-types, and diamonds for Normal-types. Bug Pokemon have a sort of beetle for their symbol looking at the type itself, but a good universal representation that would fit thematically for Terastallization could be a crystallized butterfly. A butterfly would make sense to stand for all Bug-types, but other possibilities include insects like ants and spiders, or a bee hive.
Electric
The most likely candidates for the Tera-type symbol of Electric pocket monsters are a lightning storm, or the combination of clouds and lightning. It's fairly representative of all Electric-type Pokemon, even though some Electric moves deal physical damage and behave differently in terms of animation.
Dark
Considering Dark-type Pokemon are considered to be mischievous creatures who often trick others, the best way to depict them when they Terastallize would be a crescent moon. Coincidentally, that's also the symbol for Dark-type Pokemon in several games, such as Pokemon Masters EX or Pokemon GO.
Dragon
While it may be harder to represent all Dragon-type Pokemon with one symbol, a generic dragon head would probably be the safest bet considering what Game Freak did with Regidrago, the Dragon-type Regi Pokemon introduced in Pokemon Sword and Shield. Other possibilities include sharp fangs or dragon-like wings, but they could be harder to work with.
Fairy
Fairy Pokemon are often represented as pure creatures that enjoy the moonlight and are associated with precious stones, from Diancie to Clefable. As such, the most likely Tera-type symbols for these Pokemon are the full moon, a heart enveloped in ribbons, or plain gemstones with light pink hues.
Fighting
Although many Fighting-type Pokemon have some humanoid clothing or poses that represent their martial arts affiliation, a universal symbol to use for their Terastallization process could be a big boxing glove with bandages flowing around it. Multiple Fighting Pokemon wear boxing gloves, including Hitmonchan or Makuhita.
Ghost
A symbol that works very well for Ghost-type Pokemon is the sheet-enveloped ghost design, which is simple and straightforward in what it conveys. Other options for Terastallized Pokemon with Ghost as their Tera type could be a shadowy figure or scary face that's not too dissimilar from Gengar and the Scary Face move.
Ground
Ground-type Pokemon are often associated with mountains, volcanos, and sand when it comes to their design and moves. As such, the possible Ground Tera-type symbol for Terastallized Pokemon could be a sand castle or a crystallized volcano or mountain, drawing from the common themes of creatures like Camerupt and Palossand.
Ice
Possibly the most straightforward of the types, Ice Tera-type Pokemon are likely to get a big icy crystal or snowflake as their symbol, or perhaps even stalagmites. It's possible that these symbols will be rendered in a way that makes them look icy even when the Terastal phenomenon already causes textures to become crystal-like, which could be a cool feature.
Poison
According to Pokemon Scarlet and Violet leaks, the Poison Tera-type symbol for Terastallized Pokemon is something that closely resembles a skull and bones, much like the classic symbol on pirate flags. It makes sense, considering that many Poison moves are about toxins, and it's a good way to represent Poison-types across the board - even used directly on monsters such as Koffing.
Psychic
There are a few options for Psychic-type Pokemon when it comes to a universal symbol, including spoons, a glowing orb, or maybe a big, all-seeing eye. Although spoons are the signature item for Alakazam and Kadabra, bent spoons are usually seen as a symbol of psychic powers in media. As for the glowing orb, there are some Psychic-type Pokemon that have one in their design, such as Espeon, Spoink, or the three Lake Guardians from Gen 4.
Rock
Much like Ice Pokemon, Rock-type critters have a great way of being universally represented through some kind of big boulder. It would be different enough from the symbol for Ground Pokemon, and would still convey the imagery behind rocky monsters well.
Steel
Lastly, Steel-type Pokemon have a few options when it comes to representation. A Terastallized Pokemon whose Tera type is Steel could gain a big plated armor piece on its head, or maybe crystallized cogs and wheels. Both these images are often used in Steel-type Pokemon or Steel moves, making them likely candidates.
Pokemon Scarlet and Violet launch on November 18 for Nintendo Switch.