Here's a guide on catching a level 7 Mew on the original Pokemon Red, Blue and Yellow games - before getting the second badge. It works on the newly released virtual console versions too.
Pokemon Red/Blue VS Pokemon Sun/Moon Stuck it genwunners
Red e Blue - Lyndon Willoughby
"Make your wonderful dream a reality, it will become your truth. If anyone can, it's you.
How Missingno. works for Pokemon Red & Blue