Hi there.
It is an very interesting offensive team, I appreciate a lot your team,But I see that you have counter on Chansey, I suggest you swap Counter with Seismic Toss because even if Chansey has eviolite it is not a very good physical stall, then it is generally OHKO by good physical sweepers, with counter you can not do anything against Volca Sub/Zone Sub, now you can come easily with seismic toss and you can break the substitute,then I noticed that you possess Fire Blast on Garchomp, but with the rain fire attacks are reduced, I suggest you put Dual Chop, with this move you can break substitute of Dragonite and kill him or Gengar. Then I suggest you Sleep Talk on Substitute for Tornadus-T because you are very disadvantaged against Breloom, Breloom has Spore and he can asleep Tornadus-T to kill, now you can come on Breloom easily and kill him with Sleep Talk and put Naive nature on Tornadus-T too, you can outspeed Starmie/Alakazam/Tyranitar Scarf/Magnezone Scarf/Dugtrio/Keldeo/Latias/Latios/Terrakion.
Tl;dr
Hope i Helped and Good Luck with your team.