In my opinion there is only one collection of moves for an Articuno.
Modest Nature:
252: spa., 100: def, 58: spd, 100: speed
Pressure ability
Ice Beam: for STAB and because of accuracy and power.
Extrasensory: Okay, I'll admit. My Articuno is from my Pokemon XD Gale of Darkness game, but whatever. Good effect, incredible PP, and great power.
Water Pulse: Like you weren't expecting this. I said it was from XD: Great power, great PP, good effect, and good for Fire and Rock types, which are her two main weaknesses she'll be facing.
(Filler): Mine actually has Air Cutter from Platinum. You could of course go with Ancientpower or something like that, which wouldn't be bad. You could also check her HP and see if that would be useful. I'd recommend a Ground type or a Fighting type, to deal with Steel types and Electric types respectively.