I haven't cared enough to level up Darkrai. Dark Void would be what I'd replace it with, but I can't be bothered to run around level grinding. At that point, I'd rather just ask my friend to get a stack of Rare Candies ready.
Darkrai only lives as a stalling agent in my team, so there's other ones lying in the benches. Just because I don't subscribe to tourney [Top Spin] rules doesn't mean I don't subscribe to good move strategy. That's pretty much a must in every generation of the game.