Paras and Mew have the same cry. One can only assume that those mushrooms are holy.
In the Beta of Pokemon Red/Blue there is a bit of text that shows you could originally collect special items with each badge. E.G., Brock's Badge allowed you to throw Stones at Pokemon, similar to the Safari Zone. Yes, remember kids, Badges can give you unlimited stones to throw at monsters*.
In the Beta of Pokemon Yellow there is unused script for if you battle a Pokemon in the wild without any Pokemon. It says: Oh no! You don't have any Pokemon! Run! Because everybody knows that without a Pokemon, you can't stand within 10 feet of a Caterpie.
Pokemon Gold/Silver have been called the "Beta Goldmine" as they contain so much Beta stuff it will blow your mind. There is an unused tileset for a Minecart (as seen in Pokemon Prism), and unused map for the Cinnabar Lab, an unused song which some believe was meant for the first Route, an prototype Lake of Rage map (assumed), an unused map similar to Violet City, and unused map similar to the Pattern Bush, an unused map for some crazy chicks house, an unused sprite and moveset for a Flying/Rock type Jirachi (You heard me right), and of course a Beta Safari Zone. That generation came when Satoshi Tajiri had a huge mind bomb.
Gastrodon was originally going to be in Ruby/Sapphire, but then Nintendo's marketing discovered that children don't like biodiverse sea slugs as much as they used to. They then forcably added it in Gen IV when they started running out of ideas: "Uh... A toaster Pokemon!"
As previously mentioned Pokemon Gold/Silver was the Beta heaven. Here is an unused song:
https://www.pokecommunity.com/showthread.php?t=206083&highlight=Beta+Song
Mew was copyrighted in 1992, several years before the copyright of Pokemon/Pocket Monsters. This can lead us to presume that Satoshi Tajiri had originally planned it to be in another game. My assumption is that the title would be "Weird Embryo Fairy Thing Kicks Butt and Makes the Universe and Crap."
Grimer is made from something. You know what it is? Grime.
Voltorb was actually caused by an accident at a Pokeball factory. This is no joke. Somehow Pokeballs received a strange shock, a Haunter was involved, that's about all I know. One can only guess the pure irony when it is captured.
Jigglypuff is actually Rick Astley's cousin. This is proved by his popping up randomly and singing and also this transcript from the games: "Jigg, Jigglypuff puff! Jigglypuff Jiggly! Jiggly Puff PUFF Jigglypuff."
"Hey everybody, I'm Jigglypuff. Rick Astley's my cousin yall."
Suicune, Raikou, and Entei are said to be reincarnated spirits of Pokemon that died in the tower when it burned down. Many believe that they were Vaporeon, Jolteon, and Flareon.
*Monsters not included. All accesories shown here. Some assembly may be required. If badge does not work you may need to try again. Rules and regulations apply, results may vary.
