If they didn't have compatibility between 5th and 6th gen, I'd probably just stop playing Pokemon. Hundreds of hours, 649 unique, legit Pokemon in my boxes (and quite a few more counting various forms and whatnot) are a lot to lose. At the very least, I'd never even try to complete the Pokedex again.
except you're not losing them. they are still there in your gen 5 game
You're right. I can just play the 5th gen games forever, then. --- Don't trust the smiling penguin! http://backloggery.com/mydogskip93