Some thoughts: 1)Sunny Day Cress is a pretty good answer to hail. 2)Escavalier is a good answer to her, and isn't dead weight otherwise - I've seen a lot of Druddigon on the ladder in the last week. 3)Cresselia is fun to play with in RU, and so adaptable, to the point that there is no reason not to have her on your team.
I have my opinion about Cresselia - too strong for RU. I'm interested to hear what the voters think.