Although Froslass may seem appealing due to it's high speed, it's a really mediocre pokemon. Although it's UU by smogon standarts, that's because it's serves as a spikes setter. However, that utility isn't all that useful in Reborn, since no one is changing their Pokemon a lot, and Froslass doesn't hit hard. If you need an ice type, then I can recommend you 4 options:
Ninetales: Although it has almost the same speed and special attack, it can boost it's offenses via Nasty Plot. Snow Warning is an amazing ability, since it makes Blizzard 100% accurate, enables Aurora Veil, and can t