Thick Fat is good to halve that fire weakness, and Mamoswine is part ground. A fire type might win a battle against it, but Mamoswine's EQ will leave a mark, that's for sure.
I prefer Mamoswine (Because EQ by level up), but Vaniluxe learns some interesting moves by level up too (Freeze-Dry, Hail, Ice Beam, Mirror Shot, Blizzard, Acid Armor...)
But, like zumidesu said, just go with what you need the most (Vaniluxe if you need sp. attacker; Mamoswine if you need a physical attacker).
And Icicle Crash OP nerf pls