A regular Ice move would be SE on Flying/Ground/Grass/Dragon, and NVE on Fire/Water/Ice/Steel. For Freeze-Dry, you just move Water out of the second column and into the first. That leaves only Fire, Ice, and Steel as resistances, and since nothing has the Fire/Ice typing, the only Pokemon that double-resist that are Heatran and Alola Sandshrew/Sandslash.
Meanwhile, the list of double weaknesses grows larger: in addition to things like Dragonite, Garchomp, and Torterra that were already massively weak to ice, Water forms existing dual typings with each of the other four, so (for example) Pelipper, Swampert, Ludicolo, and Kingdra all have double weaknesses. Coincidentally, those Pokemon all sound likely to show up on rain teams...