Fire/Ice To me sounds good. It is unique for a start and would just be fun to work with on principle. It kills dragons, Steels and resists water.
Remember not everything is in the typing. A lot of weaknesses can be nullified just by giving it bolt/beam.
The glaring weakness though:
X4 Stealth Rock.
Perhaps this can be offset by an ability that removes hazards? An auto rapid spin? Immunity to Hazards?
Please think about this.