Girls

Well see here: Mew is that one rare pokemon that is the cutest and most elegant of them all. Always within reach, but never close enough to catch.

Thus every Guy just wants the one rare catch that could make them happy. A prized capture they can keep for their own sake, to flaunt and to show off, and say "I caught this rare and beautiful pokemon. and She is mine"

Hope that sorta clears it up. I tried to put it into pokemon like terms =P

Yeah, but afterwards, when you are stuck with mew as your strongest and at the elite four, you think back "aww pomegranate, I wish I had charizard instead". (PS: I cheated in blue version)