Hi, cool team.
First off I suggest changing up Garchomp a little to give you a bit more insurance against Ice attacks such as Mamoswine. Try out
Yache Berry and
Fire Fang over Leftovers and Substitute to help you break through Skarmroy and other steels a bit easier. You should also move over Dragonite's EVs to
4 Defense to make sure you can switch into SR 5 times now instead of 4. You should also try. different Forretress spread opposed to that basic one. Using
252 HP / 176 Def / 88 SDef with
Volt Switch over Spikes gives you more Special Bulk and momentum for this offensive based team.
Now as others have stated, you have some problems with Pokemon like Kyurem, Rotom-W, and Keldeo. I am going to be backing Dr.Ciel's suggestion of
CB Scizor over Moltres, but I also suggest trying
LO Latios over Salamence, which gives you a steady check to Keldeo and Rotom-W alike.
Good luck!