It's always nice to see that a team can still work without the support of common moves such as Fake Out, Tailwind or flinch spams. Interesting team, HP Ice Heatran + Air Baloon seems a great combo, even if i don't like Air Baloon very much due to double targeting in VGC. I've quickly run a damage calc on Cress' Ice Beam
164 SpA Cresselia Ice Beam vs. 4 HP / 0 SpD Landorus-T: 156-188 (94.5 - 113.9%) -- 68.8% chance to OHKO
Have you thought about a Modest nature with less investment just to make sure your Ice Beam does get the kill?
124+ SpA Cresselia Ice Beam vs. 4 HP / 0 SpD Landorus-T: 168-200 (101.8 - 121.2%) -- guaranteed OHKO
Icy Wind/Thunder Wave is also a reason to debate. Icy Wind can punish the common switches on LandT/Mence/.. getting important 2-3OHKOs too, while being able to slow down ScarfMamoswine too. On the other hand Bisharp and Milotic could get a free boost and compromise your Icy Wind spam. Thunder Wave isn't able to hit Ground and Electric types and it's a single target move, but as you said it is huge against Tailwinds and also gets paralyzes.
However Thunder Wave fits better in this core, even if Conkeldurr and M-Venusaur are great checks to Bisharp and Milotic and you wouldn't be so afraid of spamming Icy Wind anyway.
164 SpA Cresselia Ice Beam vs. 4 HP / 0 SpD Landorus-T: 156-188 (94.5 - 113.9%) -- 68.8% chance to OHKO
Have you thought about a Modest nature with less investment just to make sure your Ice Beam does get the kill?
124+ SpA Cresselia Ice Beam vs. 4 HP / 0 SpD Landorus-T: 168-200 (101.8 - 121.2%) -- guaranteed OHKO
Icy Wind/Thunder Wave is also a reason to debate. Icy Wind can punish the common switches on LandT/Mence/.. getting important 2-3OHKOs too, while being able to slow down ScarfMamoswine too. On the other hand Bisharp and Milotic could get a free boost and compromise your Icy Wind spam. Thunder Wave isn't able to hit Ground and Electric types and it's a single target move, but as you said it is huge against Tailwinds and also gets paralyzes.
However Thunder Wave fits better in this core, even if Conkeldurr and M-Venusaur are great checks to Bisharp and Milotic and you wouldn't be so afraid of spamming Icy Wind anyway.
