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.