Some people think that certain Pokemon are based off legends and folklore. Feel free to post your own and I'll add it if it seems plausible enough. There can be multiple speculations for the same Pokemon.
A lot these are from prior knowledge and stuff I've heard/seen/read. I got some of them from Psypoke's forum as well. I'll just copy and paste from there and add more when I research and stop being lazy. http://www.psypokes.com/forums/viewtopic.php?f=16&t=26067
Meowth - Based off the Maneki Neko, also know as the Lucky Cat that brings good fortune and wealth. Explains the gold coin on Meowth's head.
Magikarp and Gyarados - The Magikarp is based a carp or koi, kinda the same thing. There are many version of this Japanese Folk tale but, when the strongest carp/koi is able to swim up a waterfall, it turns into a water dragon and is able to enter the gates of heaven, which explains why Gyarados is also part flying. In one of the Orange Islands episode, someone was studying Magikarp and was watching them swim upstream and evolving into Gyarados.
Vulpix and Ninetales - Both are based of Kitsune. In Japanese folklore, foxes grow one tail equivalent to how long they live. When they grow 9, they turn a golden, red, or white-ish color.
Moltes - Firebird, Phoenix. Just a generalization. It doesn't really fit a certain legend. Random fact! The last few letters of the 3 birds are the Spanish words for 1,2, and 3!
Houndoom - Based off of the hellhound, or more specifically, England's "Black Shuck". It's a huge black dog with flaming red eyes that's said to haunt graveyards and the like. There have been some sightings of the Black Shuck; whenever one sees it, a close relative dies or falls extremely ill. Occasionally, there were instances where one would die or disappear mysteriously themselves after seeing the Black Shuck. There is a story that Black Shuck entered a church, killed a man and a boy, and left nothing behind except two strange, still-existing scorch marks (which is why Houndoom is Dark/Fire).
Noctowl - In Japanese culture, Eagle Owl is revered as a messenger of the gods or a divine ancestor.
Ho-Oh - There are two for this guy. Quetzalquatl, the Mayan sun god. A phoenix in general. Fèng Huáng, Phoenix of the South, one of the Four Celestial Guardians of the Four Directions in Chinese mythology. Ho-Oh is the Japanese reading of the Chinese characters.
Whiscash - Jishin-namazu/Namazu. A giant catfish that causes Earthquakes.
Torterra - Based off of the Native American myth that the entire world rested on the back of a giant turtle/tortoise.
A lot these are from prior knowledge and stuff I've heard/seen/read. I got some of them from Psypoke's forum as well. I'll just copy and paste from there and add more when I research and stop being lazy. http://www.psypokes.com/forums/viewtopic.php?f=16&t=26067
Meowth - Based off the Maneki Neko, also know as the Lucky Cat that brings good fortune and wealth. Explains the gold coin on Meowth's head.
Magikarp and Gyarados - The Magikarp is based a carp or koi, kinda the same thing. There are many version of this Japanese Folk tale but, when the strongest carp/koi is able to swim up a waterfall, it turns into a water dragon and is able to enter the gates of heaven, which explains why Gyarados is also part flying. In one of the Orange Islands episode, someone was studying Magikarp and was watching them swim upstream and evolving into Gyarados.
Vulpix and Ninetales - Both are based of Kitsune. In Japanese folklore, foxes grow one tail equivalent to how long they live. When they grow 9, they turn a golden, red, or white-ish color.
Moltes - Firebird, Phoenix. Just a generalization. It doesn't really fit a certain legend. Random fact! The last few letters of the 3 birds are the Spanish words for 1,2, and 3!
Houndoom - Based off of the hellhound, or more specifically, England's "Black Shuck". It's a huge black dog with flaming red eyes that's said to haunt graveyards and the like. There have been some sightings of the Black Shuck; whenever one sees it, a close relative dies or falls extremely ill. Occasionally, there were instances where one would die or disappear mysteriously themselves after seeing the Black Shuck. There is a story that Black Shuck entered a church, killed a man and a boy, and left nothing behind except two strange, still-existing scorch marks (which is why Houndoom is Dark/Fire).
Noctowl - In Japanese culture, Eagle Owl is revered as a messenger of the gods or a divine ancestor.
Ho-Oh - There are two for this guy. Quetzalquatl, the Mayan sun god. A phoenix in general. Fèng Huáng, Phoenix of the South, one of the Four Celestial Guardians of the Four Directions in Chinese mythology. Ho-Oh is the Japanese reading of the Chinese characters.
Whiscash - Jishin-namazu/Namazu. A giant catfish that causes Earthquakes.
Torterra - Based off of the Native American myth that the entire world rested on the back of a giant turtle/tortoise.