You all know he's one of the Rarest Pokemon to get. And it's going to be hard. We'll it will be easier if you have Deoxys on your team or if your him. Because if your a rare Pokemon it will boost your Recruit rate as well. Also bring a Friend Bow with you so you now have about 17% and if your level 100 with friend bow and Deoxys it's 20%. If your using the Action Replay make sure to Have 100& Recruit, Infinite HP, Infinite PP, Up a Floor, and All Storage items. Make sure to get at least 3 Music Boxes just in case a pokemon knocks it out of you. No go to Buried Relic. Go up 36 Levels and start. Make sure to look for "Mew has Transformed in so n' so" And if not then that means he's out there and hasn't transformed. If you do find him in a Monster house that's good because you'll live through it because you have Infinite HP with Action Replay. Kill all Pokemon and then Mew. Make sure to get the Last hit if you have an partner.

~Fin(End)

Note: I did it twice and got him the second time. After I got Deoxys.