HP Fire is the bar none the best Hidden Power choice for Snover, because a free switch-in to Escavalier is never a good thing, ESPECIALLY for a Hail team ;o. Fire-types would not enjoy taking moderately powerful STAB Blizzards anyways.
If you're looking for alternative choices over HP Fire, then Leech Seed would work in conjunction with Protect > Ice Shard. This way you can at least put that Escavalier, Entei, or Moltres in an awkward position. Protect is also nice to scout choiced Escavalier and Entei's moves, and the 2 turns of Leech Seed means 25% health lost (+ 12.5% from two turns Hail damage and maybe 12.5-25% entry hazard damage). Leech Seed is also a great support move that would allow Walrein or SubSplit Rotom-F to set up with ease, as the opponent is either forced out or have their health leached by the snow sweepers.
I like TROP's set, but outspeeding Poliwrath is unnecessary, since the only thing it can do is Circle Throw, a negative priority move. It makes sense to invest enough Speed to outpace Lanturn (so it wont Volt Switch out before Snover can Giga Drain) and Sandslash (before it can set up SR). The leftovers EVs can be used to pump its shitty Attack or shitty defenses.
PS: In hindsight, it does help to be faster than Poliwrath to finish it off before it Rests or start pulling off +0 priority Sleep Talk Circle Throws x0