You can't actually consider running Power Herb just for a one off superpowered attack which is resisted by some common pokemon? Really, people thought the same thing about Moltres with Sky Attack and Solar Beam but things like that just never work in the long run.
rocky, how do you know? It has a different BST, its Ice moves have different BP and have a charge turn unlike those of Resh and Zek.
On the other hand, it looks like it should be in so many ways...
All I can say is there had better be a different form coming. Something like this:
Ability: Snow Warning
Cold Flare and Freeze Bolt both lose their charge, and then either it loses most of the rest of its speed to make it ultra bulky but still capable of outrunning things with Frozen World, OR, make it nice and Rayquaza - clonish. I'd sort of prefer the bulkier path.