as the others mentioned, you've got a pretty big weakness to ground-types right now
id suggest noivern because, not only does the rest of your team have really good synergy with it, since you've got 3 ice resists (4 if mamoswine has thick fat), but it'd also help you cover other types you might have issues dealing with (i.e. grass, water, fighting)
also, you can replace it later on once a better dragon/flying-type becomes available, like dragonite or salamence