Hi, cool team.
First off I suggest changing up Encore on Politoed to Perish Song
. Perish Song is a very useful move and can kill off some threatening sweepers, while Encore has decreased in effectiveness since Generation 4. Perish Song also gives you a way to defeat Calm Mind Reuniclus and SubDD Gyarados. I also suggest changing up Starmie's set a bit. I suggest changing up to Psyshock and Scald
over Ice Beam and Thunderbolt. This allows you to defeat Keldeo. I also suggest using a Timid Nature
to actually outspeed many of these threats such as Terrakion, Keldeo, and Infernape. I also suggest turning Mamoswine into a Life Orb variant
with Ice Shard over Stealth Rock
to adjust for a future change. A Jolly Nature
is suggested for this set to give you a solid answer to Breloom by outspending it and taking it out with Ice Shard.
You have some severe problems with Offensive Starmie, dragons, and Rotom-W. Tornadus - T also does a huge number on your team. Having no resists or anything to outspeed it I suggest changing up 2 Pokemon to cover all of these threats at the same time. The weakest links to your team probably have to be Jellicent or Gyarados. Jellicent does not really do too much for your team as you don't need a spin blocker too much and it can easily be replaced for a better Pokemon. I suggest using Ferrothorn
over Jellicent to give you a counter to Starmie and Rotom-W while giving you a steel type to sponge dragon type attacks. Ferrothorn gives you a great support option for your team. I also suggest using Specially Defensive Rotom-W
over Gyarados to give you a solution to Tornadus - T. Rotom-W gives you some great momentum for your team and also guarantees that you can handle Volcarona.