The team seems particularly weak in Rock Polish Landorus, I suggest therefore Memento> Stone Edge
on Dugtrio, which decreases the stats of the Pokemon opponent, allowing you to enter your Victrebell Growth in the field to use a more secure, also as mentioned above in addition I also suggest Venusaur> Victrebell
, as with most bulkyness and more speed with this set of 72 HP / 252 SAtk / 180 Spd Timid
Nature with to outrun Scarf Latios and Growth - Sludge Bomb - HP Fire - Giga Drain
. in my opinion HP Ice does not serve as a +2 with the support of Stealth Rock the dragons you can still kill them using Sludge Bomb, HP Fire is for Steel Pokemon (like Ferrothorn, and Forretress Skamory for example).
Last thing I suggest is to use Ninetales with the set Chesto Rest
in my opinion is one of the strongest that we are, if not the strongest, because what matters is that Ninetales can survive the most stretch to win the Weather War, since Dugtrio with Arena Trap can kill through pretty much just Tyranitar, and Hippowdon you can not view its huge bulkyness for Politoed however not all the variations of his moveset can be killed with Dugtrio.
With the set Chesto Rest can save you from possible status Toxic type from Rest well, which is important, since it is a bit 'more difficult to manage the Weather setter infatuated with each status.
Good luck, with your team!