What are reasonable non-legendary pokemon to put up on GTS to get the legendary birds? I'm about to start working on filling in the Kalos pokedex and I figure I'll need them eventually if I want to get a complete national dex too.

I'm not willing to give up my own legends unless I have multiples and I don't have the ability to clone.

I was able to get several starters and a few other national dex pokemon from WT and GTS, but haven't had success with asking for any of the birds yet.