Skarmory and Mawile from me.
Skarmory, I've always been in love with the bird since I first saw it in Sapphire. Too bad the thing is so hard to catch, but regardless it's a cool-looking bird and also a great battler as well.
Now if I don't put in Mawile on my vote as well then idk what I'm doing with my life hahaha. Mawile's super cute, and now that it has a mega evolution, super strong. <3
I've never actually used a Mawile 'til I played Pokemon Y though, since most of the time Mawile is post-national dex only, and I've never owned Ruby as a child. I was stuck with Sableye haha. But regardless, you should know how disappointed I was when I learned that I can't catch Mawile in Sapphire. Oh well. </3