No, ground is weak to Ice giving Flygon and Garchomp weaknesses to Ice (4x) and Dragon (2x) attacks (Salamence, Dragonite and Rayquaza are weak to Ice [4x], Rock [2x] and Dragon[2x]).
Granted the ground pokemon resist rock he'll still have a large weakness to both Dragon and Ice attacks.
Take out Dragonite and Latias, your current team has 5 weaknesses to Dragon as well as Ice (Dialga's Dragon/Steel typing is neutral to both), since you're the Dragon GL your opponent will be using Dragon and Ice attacks the most.
IMO put in a Magnezone (combined with a Salamance or Rayquaza they will resist every type in the game [Magnezone is weak to Fire [2x], Fighting [2x] and ground [4x] the only other type it doesn't resist is Water [1x]).
As for your final pokemon, I suggest another Steel pokemon (maybe Registeel to help with Sp.Def as well as Defence) as they resist Ice and is the only type to resist Dragon.
I would like to know how many people here are familiar with the advanced part of pokemon (IVs, EVs, Natures etc) and how many people would like to learn about it.
[Edited by ghost42, 12/28/2008 6:01:56 AM]
the same with my team