A new type has not been added to the Pokemon games since Fairy-type was introduced in PokemonX & Y. Usually, a new type is introduced into the meta in order to balance the current type charts. However, a new type can also be an opportunity to re-imagine older Pokemon who may fit it better than their current typing.
Many Pokemon fans have imagined what it would be like if Game Freak added a "Cosmic" type in a future Pokemon game. This typing would be beneficial in classifying certain extra-terrestrial-inspired Pokemon, who usually end up by default as Psychic-types. These already-existing Pokemon would be great candidates for Cosmic-types.
12 Clefairy / Clefable
According to Pokedex entries, Clefairy stores moonlight in its wings, which allows it to fly in midair. Along with its evolved form, Clefable, these first-generation Pokemon only appear during full moons. Their strong connection to the moon makes them easy candidates for a potential Cosmic-typing.
Since Clefable already benefits from being a Fairy-type, it can easily be a combined Cosmic/Fairy-type. Plus, this could benefit Clefable greatly in competitive play, especially if, for instance, the Cosmic-type allowed it to be resistant to Steel-type, one of Fairy's two biggest weaknesses.
11 Xatu
These Psychic-flying types were introduced in Pokemon Gold & Silver, and have gone through few changes since their debut. Xatu, the fully evolved form of Natu, is a mystical Pokemon according to Pokedex entries and has the ability to see the past and future.
While Psychic is already a fitting type for this Pokemon, an argument could be made that replacing Xatu's Psychic-typing with Cosmic may be beneficial depending on Cosmic's strengths and weaknesses. Nevertheless, giving this kind of update may be what Xatu needs to find a better place in the competitive field.
10 Jirachi
Jirachi was introduced as a Mythical Pokemon in Generation 3, only being available to players via an exclusive Event. Jirachi was also featured in the animated Pokemon movie Jirachi: Wish Maker, where it awakens for the Millennium Comet festival to find a friend. It even has the power to grant wishes once every thousand years.
What makes Jirachi confusing is that its current typings, Steel and Psychic, don't seem to fit its lore and abilities. If Jirachi was pure Cosmic-type instead, that would make much more sense. Hopefully, pure Cosmic-types would be viable enough in the competitive meta to cost Jirachi the great typing that is Steel/Psychic.
9 Deoxys
Of course, many Legendary and Mythical Pokémon are shoe-ins for Cosmic-typing, with Deoxys being perhaps the most obvious of them all. This pure Psychic-type Pokemon was formed from the mutated DNA of a space virus and can shapeshift into several forms that affect its base stats.
While many Psychic-types could lose their current typing in place of Cosmic, Deoxys could keep its Psychic-typing and become a dual Psychic/Cosmic-type Pokemon. This would be beneficial not just for Deoxys's competitive viability, but for Deoxys's lore, which states that it has the ability to wield psychokinetic powers.
8 Dialga & Palkia
A new generation of fans has just encountered these Legendary Pokemon in Pokemon Brilliant Diamond & Shining Pearl. Dialga is regarded in Pokemon lore as the controller of time, while Palkia is a deity that can alter the reality of space. Given these time-and-space-altering abilities, these Pokemon are easy choices for a possible Cosmic-typing.
The only issue is, Dialga and Palkia are currently Steel/Dragon and Water/Dragon, respectively. Replacing their Steel and Water typing with Cosmic would effectively make them the same type. To distinguish them, it would possibly be beneficial to replace their Dragon-typing, making them both Cosmic-type and also removing their weakness to the Fairy-type.
7 Cresselia
Another Legendary Pokemon introduced in Generation 4, Cresselia is currently a pure Psychic-type Pokemon who resembles the crescent moon. Similar to Clefairy and Clefable, Cresselia's strong connection to the moon makes it a prime choice for Cosmic-typing.
However, as a pure Psychic-type, Cresselia benefits from STAB Psychic-type moves, as well as power over Fighting and Poison types. Replacing its Psychic-type with Cosmic would essentially force it to be re-imagined entirely. Perhaps Cresselia could benefit from being a dual Cosmic/Psychic-type.
6 Gothitelle
Another pure Psychic-type Pokemon, Gothitelle was introduced in Pokemon Black & White, which also happens to be its color palette. Like Xatu, Gothitelle can predict the future based on the movements of stars it can see from thousands of light-years away. Because of this, it would be an easy choice for Cosmic-typing.
However, Gothitelle's mostly-Psychic moveset would mean it needs an overhaul to accommodate a potential Cosmic/Psychic-typing. Giving Gothitelle access to whatever Cosmic-type special moves could be introduced would not only allow it to have STAB but would also widen its very limited move pool.
5 Elgyem / Beheeyem
Elgyem and Beheeyem and pure Psychic-type Pokemon who debuted in Generation 5. These are perhaps some of the strongest candidates to argue for the introduction of Cosmic-type, as they are based on aliens that can manipulate humans and Pokemon alike. Even their Pokedex entries claim that they first appeared after a UFO crash.
As such, Psychic-type wouldn't really fit Elgyem and Beheeyem if the Cosmic-type was available in the games. It makes the perfect argument for separating Cosmic and Psychic, as Psychic-types should only include Pokemon with psychic abilities, while Cosmic-types are Pokemon from or who have access to other worlds and dimensions.
4 Hoopa
Speaking of Pokemon who have access to other worlds, Hoopa is a Mythical Pokemon introduced in Generation 6. With its signature gold rings, Hoopa can utilize them as portals to send any person, Pokemon, or object across space. It currently has two forms: Confined (Psychic/Ghost) and Unbound (Psychic/Dark), characterized by their very different appearances.
Like Dialga and Palkia, keeping these two forms distinct would be a key to altering Hoopa's typing. Changing it from Psychic to Cosmic and keeping the Ghost and Dark secondary typings would be the best way to preserve these differences.
3 Minior
While Rock/Flying-type is certainly a good fit for this meteor-based Pokemon, it certainly feels like the kind of Pokemon who would make the most sense for a potential Cosmic-typing. If it was Rock/Cosmic-type, that would probably be the best way to preserve its lore while also taking advantage of this new typing.
However, the benefit of Minior losing its Flying-typing is that it doesn't learn many Flying-type moves to begin with. The only Flying-type move in its learnset is Acrobatics, which is learned via TM. By replacing Flying with Cosmic, Minior could widen its movepool and take more advantage of its secondary typing.
2 Solgaleo / Lunala
The Legendary Pokemon that serve as the mascots for Pokemon Sun & Moon are easy fits for Cosmic-type. By replacing both Lunala and Solgaleo's primary Psychic-typing with Cosmic, they would more accurately represent their own lore as otherworldly beings that absorb and dispense light.
What makes Solgaleo and Lunala even more obvious choices for Cosmic-type is their pre-evolutions, Cosmog and Cosmoem, who are both Psychic-types. It seems like a no-brainer that two Pokemon whose names come from the word "Cosmic" should have Cosmic-typing as well, right?
1 Eternatus
This Legendary Poison/Dragon-type is a huge part of the story in Pokemon Sword & Shield. According to its Pokedex entries, Eternatus was born from a meteorite that landed in Galar 20,000 years ago. The energy that allows it to stay alive also bends space and time, incorporating a lot of elements of previous Cosmic-type candidates that have been previously brought up.
If Eternatus lost its Poison-typing in favor of Cosmic-type, that would make it lose its weaknesses to Psychic-type and Ground-type, two very powerful types in the meta. This could possibly result in Eternatus becoming more overpowered than it already is. Hopefully, Cosmic-type would have enough weaknesses to keep this Legendary Pokemon at bay.
