So, I got a Gardevoir that the judge in Kiloude City claims the Special Attack and Speed are 'stats that can't be beat'.

I'm aiming to get a Gallade with decent stats out of her via breeding, but all I have to breed her with is a ralts with 'can't be beat' HP/Special Attack, or a Ditto with 'can't be beat' HP/Attack. Which should I breed with her, and which should hold the everstone/destiny knot if I want to get good offspring? Both Gardevoir and the Ralts have Synchronize by the way.