You need a Snorunt. I think, the pre- evolved form of Froslass and Glalie.
Then you need a certain stone I believe. Try the new stones.
Shiny Stone
Dawn Stone
Dusk Stone...
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You can evolve a female Snorunt with a dawn stone.
Use dark or fire type moves.
Snorunt can either evolve into Glalie at level 42 or into Froslass with a Dawn Stone if its female
Unfortunately, you can't get a Froslass in Emerald. Froslass wasn't introduced until the Generation IV games (Diamond, Pearl, and Platinum). You can get Snorunt (in Shoal Cave during low tide), but you won't be able to evolve female Snorunt into Froslass until you move it to a later game. If you do, you can evolve it using a Dawn Stone.
snorunt is a ice type Pokemon , it's evolutions glalie which is ice only (level 42) and froslass use dawn stone on snorunt ice and ghost