So I'm going to guess that for Articuno the only issue is the ability?
The stats aren't anything special as any defensive potential is ruined by its horrendous defensive typing. It's too slow to sweep even after a CM boost or 2. So the only suggested changes I'll make is the ability.
Absolute Zero: Freezes those who make contact with Normal, Water, Ground, Fairy, Dragon, Grass, Dark, Flying or Fight Moves only. OR the freeze only lasts 1-2 turns, and onkly has a 30% chance to land... or all 3? Or just scrap the ability altogether?
The fact most SE moves don't freeze the user mean
Otherwise I can't see Cuno being too good if its Ability were changed unless there's something I'm missing.
Sure 90/150/120 isn't bad defenses but Avalugg has better physical with 95/184, can use an item and isn't double SR weak.
So is there anything else I'm missing about the Ice Birb? With the changes I propose all of its weaknesses will not be resisted so Flare Blitz, Iron Head, Bullet Punch, Accelerock and Head Smash to your hearts content. You can also U-Turn out without Freezing yourself for some reason.
Not sure this is nerf enough. Taking half the type chart away from Freezability hopefully means sweeper types have a move that can hit it... most do though as I'm sure Rock, Fire and Steel are decently common coverage. Sure it punishes Outragers and Choice users.
Feel free to tell me I'm wrong.
So the Only Articuno change is the ability IMHO.