Froslass is a great Spiker. Sure, she can't really match up to Forry or Skarm, but her Ghost typing gives her a few vital immunities, with Rapid Spin being of most note. You're not likely to find too many uses for a Spiker set in-game though, so you're better off going for a sweeping or support set. Here's a good example of the former:
Froslass@Choice Specs
Nature: Modest (+Sp.Atk, -Atk) or Timid (+Spd, -Atk)
Shadow Ball
Ice Beam
Thunderbolt
Psychic
Pretty much a BoltBeamer. Shadow Ball and Ice Beam receive STAB thanks to Froslass' dual typing, and coming from a Specs boosted Sp.Atk (which will cap around the 370-390 mark), they're likely to hurt majorly. Thunderbolt and Psychic add to type coverage.
Timid is probably the preferencial nature, which will yield a max Speed stat of 350, which should be sufficient to outrun the likes of Garchomp and Salamence. Modest is there in case you want a greater Sp.Atk, naturally.
Obviously you'll want to watch out for alot of standards such as Blissey, who'll wall the crap outta you. In addition, you'd do well to avoid Dark types, including Tyranitar and Weavile, who'll you have little offensive impact upon while being simulataniously KO'd with Pursuit/Crunch and the like. Any hard hitting Pokemon should be avoided, with the exception of Garchomp and Salamence, who you should outspeed.
I'd love to offer a supporting moveset also, but I'm not really good at those, so I'll leave them to better members to suggest.
EDIT: Your current EV spread will suit this Froslass to a 'T', as it's Speed and Sp.Atk are all you really need for the set anyway.
-OL
