>>38443971It is amazing offensively like people say though. That's its entire issue. It's so good offensively that you don't need ice STAB, you can just bring a water or electric Pokemon with an ice move and get all the benefits of murdering dragons, flying, ground, and more. Your water type can kill grass types. Your electric type can use just half a moveset to hit 99% of the game for 100% damage output.
Your supposed vacuum isn't Pokemon. Of course ice is poorly balanced when it's only specifically an ice type Pokemon who can use ice type moves against other single typed Pokemon, but common fire/steel/water types include things like fire/flying types, steel/grass types, etc. Putting something in your example like Heatran against, say, a Keldeo because it used HP Ice is an incredibly stupid idea and the actual worst possible consequence of it was sending out a fucking Heatran against a Keldeo.