It can stall through an entire Dynamax with first Ice Face, then Hail, and finish off with Protect. It can also learn Aurora Veil for extra protection. It also has decent stats. So why don’t people use it?
There are much more greater ice types than Eiscue, such as Mamoswine, Lapras and Weavile. It's attacking stats are both mediocre and bad, its speed is terrible, and it's movepool is terrible. Despite it's ability, Eiscue is not that great for the competetive scene.