What I've noticed about Cresselia is that it almost forces people to switch to a different Pokemon if they don't have what SV calls a "niche counter". What I was thinking is instead of actually switching Pokemon around on a team, switching moves around, so there are some ways to counter the stat boosts. Without the stat boosts, Cresselia is basically useless and can fall prey to Megahorn or Bug Buzz.
The thing is, there are perfectly acceptable Haze users out there that aren't usually seen as Haze users, such as Omastar, and the more obvious ones, such as Cryogonal, especially the latter in fact. Cryogonal is almost a perfect Cresselia counter as it has huge Special Defence, Haze and Toxic. Add in Rapid Spin and Ice Beam and you have a viable set.
Phazing, too, can be an option. Take Roar, for example. Looking down the table of the Pokemon that can learn it, I see what is basically half the RU tier, from the often-debated fourth slot on Entei to the defensive might of Aggron and Steelix, and most of the other top threats there as well (Nidoqueen, Moltres, Sceptile... the list goes on). I admit that not all of them are viable with Roar, but it's a start.