Remember Missingno? The pokemon everyone thought was the 152nd Pokemon. To catch Missingno look at my pokemon cheats page. If you use a max repel while you to catch Missingno you can find any pokemon including Snorlax.
Catching him will make your graphics a little funny or you could loose all your pokemon. And changing his name to Mew will not make him change into Mew. Missingno is pokemon 000 and is a pokemon mixed with a bird. It's attacks are water gun 25/25 water gun 25/25 and sky attack 5/5.