Depends very heavily on your Blissey, Minwu, but Natural Cure is the standard even if you do have Ice Beam. There's something very nice about being able to switch into any status and have it just go away as soon as you leave, and if Blissey is your Heal Beller/Aromatherapist, you'll want to make sure she can do her job without the interference of sleep/repeated parahax/lucky freeze. However, if you really want to mess around with haxing people or have an excess of other status absorbers (say, more than one other guy with Guts, Sleep Talk, Natural Cure, possibly a Heal Bell Celebi already on your team...) you could use Serene Grace, possibly also with Thunder/bolt or Flamethrower for other status.
Generally, if you can only have one attack, Seismic Toss is going to deal way more damage than anything else you can use. It does leave you dead to ghosts, but Dusclops is going to have a hell of a time actually killing you, and Gengar won't like any Thunder Wave action unless he's got Sub.
Also worth noting is that, aside from going for the freeze chance, Ice Beam isn't going to do much of anything without at least some investment in Special Attack EVs. You'd need something like 200 EVs to OHKO a standard Salamence even with its 4x Ice weakness, so that should give you an idea how much damage you'd be dealing with fewer EVs against things that are less weak to Ice or generally more bulky.
So... it depends, but hopefully I touched on most of the things you'd want to consider.