Ok, so, I found an interesting fanfic about the "MissingNo. Glitch" or "'M Glitch". Then I searched it on Youtube, and I found a video that had a very plausible theory about the "Pokemon" 'M and the fact that it evolves into Kanghaskan. (SPOILER ALERT!) it's a Marowak's data, pixelated and hidden in the Generation I games. Yes, I'm sure many people know the legend about Kanghaskan; as Kanghaskan always has a baby, purple version of itself in the pouch on it's chest for no apparent reason... well, basically, the Kanghaskan Legend gives a reason; (lots of semi-colons ;) The legend goes as follows:
"When a Kanghaskan's baby leaves it's mother's body for too long (Usually if it's mother dies), instead of growing into a Kanghaskan, it becomes a Cubone. The Cubone then evolves into Marowak, but never returns to it's Kanghaskan form."
Because of this, the theory I found, and totally agree with, was decided, with the help of some info leaked about the original versions of the GI games; in the original versions, Marowak was supposed to evolve into Kanghaskan, but this was scrapped for some reason. Because it would have taken too long to take out the evolution of Marowak into Kanghaskan, as it would have meant deleting and reanimating one or both the Pokemon (Marowak and Kanghaskan), they decided to create a new form for Marowak, making it still evolve from Cubone, but not into Kanghaskan.
But, the evolution data was never deleted. Just separated from Marowak and Kanghaskan, subsequently separating them. So, basically, the evolution data, which was hidden by the game's developers within a secret code in the game, has overtime become the distorted pixels of a Marowak, in the shape of a rectangle with a small square at the top (Random, eh?). This Marowak, when discovered in the way shown below, is able to evolve into Kanghaskan. The Pokemon 'M and it's evolved form have erratic stats and levels, in one example I saw starting at lvl 80, evolving into Kanghaskan after levelling up once and becoming lvl 100, and then after levelling up again, became lvl 70. This lvl 100 had 294 ATTACK, 8 DEFENSE, 82 SPEED, and 24 SPECIAL. Yes, 8 DEFENSE.
The famous method for finding MissingNo. Is, basically, as follows:
Fly to Viridian City, go talk to the man who teaches you how to catch Pokemon, say NO, he shows you how to catch Pokemon. Then you must fly to Cinnabar Island, go to the East side, surf up and down the edge, and you can find it, along with Pokemon of strange levels that sometimes shouldn't even be there. When/ if you catch 'M or MissingNo. (They claim to be different, but their just different codes for the same thing; it's complicated) the Pokemon, if under any status effect, will suddenly be cured of it after catching it, and you must beet it to get rid of it. Then, if you put 'M/ MissingNo. at the front of your party, then get in a battle and win it, it levels up to a random lvl, then evolves into Kanghaskan, changing from "Bird" type to "Normal" type.
The origin of MissingNo.'s name comes from the fact that it has no number and the origin of 'M is likely Marowak (M), although I don't know what the apostrophe ' is for.
If I could give any advice to anyone who tries this glitch: save before you try it, and DO NOT SAVE AFTER YOU TRY IT! If you do save, the effects it has on the game can become uncontrollable for some reason, and simply deleting the save file sometimes doesn't stop it. So, this glitchy world that is created made me think; "what if this happened IN THE POKEMON ANIME?" and the story that follows, starting next chapter, is what I think would have happened, and how Ash and the gang would stop it.