muahahaha I have solved it using my extreme pokeskillz!
Ok, you know how to get to faraway Island you need a cheat device (action replay?) well once you're there at the island, save your game and turn off your gameboy. then take out the cheat device and play your game normally, go into the grassy area and go into the passage way. the reason it kept taking you backwards is because everytime you tried to enter a new area it would warp you to faraway island. but then it should work, mew will be there and you get to play hide and seek, then catch him! i'm about to fight him now after I play hide and seek, i'll tell you what his level is.