2. Missingo - Pokemon Red/Blue/Yellow (1996)
http://www.youtube.com/watch?v=-tOyBahKkbk If you grew up as a kid in the '90s, there's no way that you haven't heard of Missingo, who is arguably the most famous Pokemon never invented. Missingo, for the sake of a quick explanation, was a glitch Pokemon that was literally "missing" its number and wasn't supposed to be in the games at all. It didn't actually exist, it wasn't designed as one of the 151 Pokemon, and yet it was possible to catch it. To do so, players would need to first acquire the "moves" (remember moves?) fly and surf, and head to Cinnabar Island. Before that, though, they'd talk to the old man in Viridian City - the one who taught players how to "catch 'em all" in the beginning. When they'd arrived at Cinnabar, they would use surf on the island's eastern side. When they'd next encounter a Pokemon, it'd probably be Missingo, who physically looks like a glitch (but could sometimes take on other, weirder forms). How did Missingo improve Pokemon, then? Well, once you caught the little chap, whatever item was in the 6th slot of your bag would clone itself. 128 times. So, no, technically the glitch isn't an improvement on the game, 'cause it's ugly and erroneous, but for those players who wanted to clone important items (Master Balls, for example) so they could keep playing without getting bored, Missingo was like a gift sent from, uh, Mew. He's like God, right?