I don't think there are any. I haven't ran into any. You can buy the water, lemonade, and Soda pop in various stores in Lumoise though.
I thought Amura learned it. I'm not training mine but I thought it was learned by the lower form. You may have passed it up already. Try to see if you can steal some Heartscales off of Luvdisc and see if its on her list at the Move Relearner's place.
I haven't seen a Gardevoir use Moonblast. It may be something she should have learned before, maybe its a move that is listed as [--] which would mean you'd have to go to the Move Relearner to teach it. See if you missed it or go until you hit 80. Not many learn moves after 80 so if you hit that and still don't get it, either she doesn't learn it naturally or you missed it.