Dragon Ball and Pokemon are two of the biggest names in anime, with the latter also being a premiere video game franchise. One video game series that isn't as mainstream, however, is fellow Nintendo franchise Earthbound. This series, known as Mother in Japan, is perhaps most well-known for its quirky sense of humor, having its final entry stuck in Japan and protagonists Ness and Lucas being playable in the Super Smash Bros. games.
Earthbound's niche status hasn't kept it from inspiring rumors and possibly other franchises, though. In fact, the villain of the first two Mother games might have influenced both Goku's nemesis and a Legendary Pokemon. Here are the theories behind how Giygas, Frieza and Mewtwo are all possibly connected.
Akira Toriyama has been rather candid about what led to the creation of Frieza. The character was created around the time of the Japanese economic bubble, which led to the presence of several unscrupulous real estate sharks who took advantage of people for profit. Seeing these kinds of people as the absolute worst, Toriyama made Frieza into a sardonic intergalactic warlord who enslaves planets for profit.
While this is the official origin for the character, many fans have noted something else. The character bears several physical similarities to Giygas from Nintendo's Earthbound series, with Giygas's design looking like a cross between Frieza's final slender form and his bulky horned form. Both aliens are meant to be a sort of penultimate evil, as well. Mother 1/Earthbound Beginnings released in July 1989, with Frieza making his debut in the original Dragon Ball manga about three months later.
This time window allows for the possibility that Toriyama was inspired by the Nintendo game, though it is somewhat unlikely. It's the next theory, however, that supports this one, bringing things full circle.
The original pair of Pokemon games would debut in the late '90s, and the penultimate monster in the games was the powerful clone Pokemon Mewtwo. The purple humanoid was much more fearsome in appearance than its progenitor Mew, and this design, as pointed out by Redditors, is eerily familiar.
With its slender frame and color scheme of white and purple, the creature is highly reminiscent of Frieza. Its ears even resemble the similar ridges on the top of Frieza's head in his second form. Likewise, Mewtwo bears even more resemblance to Earthbound Beginnings' design for Giygas. This resemblance is even stronger in the anime's flashbacks of Mewtwo's origins when the creature is being developed in a lab. Keep in mind also that Ape Inc., who developed the Earthbound series, would later become Creatures Inc., who develop the Pokemon games.
Satoshi Tajiri, the main man behind Pokemon, has admitted candidly that many of the initial designs and ideas stemmed from his love of anime. Dragon Ball's popularity would have been inescapable at that time, so if this is true, there's no doubt that Frieza's design, which was itself possibly based off of a Nintendo character, went on to inspire another one. Giygas and Mewtwo both boast vast psychic powers, making the link somewhat stronger.
This theory sounds a lot more plausible, especially since it's backed up by firm statements from Tajiri himself. Keep in mind that, while the original games didn't release until 1996, production on the first entries in Pokemon began all the way back in 1990. This production time would have allowed for Tajiri to be inspired by Frieza's many forms, with the span of time being much more believable than the mere months between the debuts of Giygas and Frieza.
It only sort of lends credence to the Giygas/Frieza theory, however, and even that's only by virtue of things coming poetically full circle. There's simply not enough evidence to fully support the idea, especially given how comparatively niche Earthbound was even in Japan. On top of that, Giygas' design was only totally viewable when fighting him at the game's conclusion, and the design was rendered in rather low-quality 8-bit graphics.
This makes it a bit hard to buy that the game inspired Toriyama when he created Frieza, so it's possible that fans are simply reading too much into uncanny similarities with this theory.