>>33787777>>33787806This, plus, some of the things that Marshadow would use ice coverage for, Landorus Therian and Mega Salamence, have Intimidate, which turns Ice Punch into a two hit ko, while hidden power stays a one shot.
I think the question should be whether you want ice coverage or not, rather than which one to use. If you're not running HP Ice, just don't bother with Ice Punch and run a Marshadium set instead and just swap out against those Pokemon, because you'll probably die trying to use Ice Punch, at least against the things Marshadow wants ice for the most.
