Hydro Pump + Freeze-Dry, as expected, is pretty comprehensive coverage. The only Pokemon that resist both moves are Smoochum, Jynx, and Shedinja, but none of those Pokemon are in the game. Water/Ice with Thick Fat (Dewgong, Walrein) can pretend to resist both, so Dewgong is at least an option, for whatever that can do in return. Beyond resisting it, DLC2 also gave us access to a bunch of legends, including Regice--Ice-types are infamously bad with their defensive reputation, but they actually work pretty well here, having the key resist on the double-STAB Ice moves, and a Special Defense that can get over 500 is about as good as the typical resistance to Water. But why not...612?
Frosmoth @ Light Clay
Ability: Ice Scales
Calm Nature
- Aurora Veil
- Struggle Bug
- Quiver Dance
- filler attack (Giga Drain/Bug Buzz/etc.)
Frosmoth offers soloing and online support options. If Iron Bundle is going to open with immediate Aurora Veil, you can take advantage of the snow for your team too. You're not going to outspeed out of the gate, but with all this special bulk, Hydro Pump should deal less than 25%, and even has a convenient chance to miss, then starting with screens gives you even more of a runway. If you want, you can put the speed at 206 so you start outspeeding with the first QD, and can then start on the Struggle Bugs to get to +1 vs. -1 for tanking the next hit. Otherwise, dumping the rest in HP and SpA is fine, knowing you won't be faster until the second QD in that case. When you have more QDs down and are ready to attack, Bug Buzz is the most powerful option, or Giga Drain lets you heal off whatever pittance of damage the boss is dealing by this point. This is a case where you might actually want Tera Stellar if you can afford the shards for it: you don't really want to give up the ice typing, but going tera-ice for ice moves as your damage source isn't all that helpful.
