Pokémon: Will There Ever Be A Mewthree | Screen Rant
Pokémon has added many species that are the result of mad science, and there is a real possibility that Mewthree could exist in future games.
Mew and Mewtwo made their debut to the Pokémon series during Generation 1. The Kanto Legendaries have been long-time favorites of the Pokémon community, with Mewtwo being a powerful Legendary that frequently makes the Pokédex for most Pokémon games. Mewtwo is the product of genetic experiments using Mew's DNA, as many Pokémon fans learned during Pokémon: The First Movie, and it's status as a clone of Mew is why it is possible that Mewthree could potentially exist.
While there haven't been any indications from the Pokémon series developers to show they are planning to add Mewthree to current games or movies, players know from watching Pokémon movies about Mewtwo's origin that the technology to create more clones is still available. Mewtwo itself is able to create clones of the Pokémon it kidnaps from trainers who came to battle it in Pokémon: The First Movie. The question is less about if it is possible for Mewthree to exist, and more about if the developers will ever consider adding Mewthree to upcoming games.
The closest fans have seen to Mewthree in recent games was the addition of two Mega-evolution forms for Pokémon's Mewtwo that were introduced in Pokémon X and Y. However, because mega-evolution isn't permanent, and requires an existing Pokémon to be used, it doesn't count as a different Pokémon. There is encouragement for fans who may want to see Mewthree however, as recent games have showcased available technology in the Pokémon world and how far it has evolved through each Pokémon generation. Sun and Moon's Aether foundation explores just how far technology has come compared to the first games in the series, and the advanced technology would make it feasible for another group of scientists to attempt making another genetically-altered Pokémon clone from existing DNA.
While the Pokémon games and anime haven't ever introduced a Mewthree, fans who read the manga may have noticed a different Mew variant tucked into the narrative. According to Pokémon Fandom Wiki, a "Mewthree" appeared in the Manga when Red's Clefairy genetically merged with Mewtwo's DNA. Clefairy was able to revert back to normal however, so this "Mewthree" doesn't really count as another version of Mew. This Mewthree doesn't ever appear in the current Anime or any of the games, making it a unique find for those who have kept up with the Pokémon manga.
With the Pokémon series celebrating its 25 year anniversary during 2021, and the rumor of new games potentially coming this fall, it is possible players could see Mewthree added as a way to connect players back to the base 151 Pokémon of the original games. Despite the fact that it is possible, there is currently no information about what projects Game Freak may be working on, or any confirmation for if those projects will explore new variants of existing Legendary Pokémon. This may mean Pokémon fans will have to rely on their imagination when deciding what Mewthree could potentially be like, but at least they can continue to enjoy the appearances of Mewtwo in currently-released titles.