The majority of dragons against a Ice move = dead. Most of them suffer from having a double weakness to Ice by either being Dragon/Flying or Dragon/Ground. Dragonite with his Multiscale ability can probably survive a STAB Ice move, not sure I haven't tried it, but the likes of Flygon, Salamence, Garchomp and Rayquaza will easily fall to Ice moves.
Ya. Alteria has the dual weakness to Ice yes, but it actually has decent defenses so it might surive a non STAB Ice attack. And if you're just going to use it for Fly, then go for it. I personally don't make a big deal out of the Pokemon I have just for Fly, it's usually the first thing I can find, for example I'm using a level 10 Noctowl I found in a Headbutt tree on my Pokemon Crystal file atm for fly.
Altaria is one of the most under-rated Pokemon! Great defences, above average attack stats, decent speed, a fantastic move-set and is one of the few Pokemon with Dragon Dance & Roost that are actually useful with them..
I've never actually used an Altaria, there were always better options. Or you could get them at the point of the game where your team is already set. I'm not adding new pokes to my team after the 7th gym.
Does anyone know if/when they'll announce all the new Pokemon for gen 6?
Most announcements most likely won't be until 1-2 months before official release with a few leaks in maybe July or August, and even then the majority of Pokemon won't be announced and well have to play the game to know them all.
"It's not so much as preventing insanity... As much as it is taking advantage of Insanity..."
[This is where I'd put one of my drawings I worked hard on in my sig, but since I'd have to spring five bucks to do so, I'll just put me photobucket link here.]