By YOUR information I just thought of what MIGHT be a glitch, Almond. You said they had to store your player's name on the side of Cinnabar Island, right? Well, if thats true then they must store the info for all the unavailable pokemon SOMEWHERE. So the creators probaly created a little island surounded by some kind of physical boundary so no one could acess it. But a hacker cheated and some how luckily got there, where he found all the stored pokemon and thus encountered them in the wild. If I'm wrong, feel free to correct me. But that just came to my mind hearing that.