Hey man this is a really well thought out offensive team, and I am just going to be nitpicking here. There are some Pokemon that look threatening, but most can be played around with smart plays. Frankly the only Pokemon I can think of that looks exceptionally dangerous is an opposing non choiced Thundurus-T. Your team can fall to it pretty easily, with Starmie being the only Pokemon that outspeeds and KOs. Although smart playing can beat it, one bad prediction can ruin the match. For this reason I am going to make a rather unorthodox recommendation of a Yache Berry
on Thundurus-T. With Modest, Thundurus has no chance to outspeed opposing Thundurus-T's, but with a Yache Berry it can live a Hidden Power Ice and KO back. Of course this is slightly situational, but it does serve as a semi-reliable check. Yache Berry also gives Thundurus-T more longevity, albeit slightly less power.
Also like other have said, I am not the biggest fan of Substitute on Politoed. Like others I have a moveset replacement for it, but I think this replacement will suit your team a little bit better. I recommend a ChestoResto
set on Politoed. With this set, Politoed can feign a choiced item, possibly scoring a ko against opposing boosters, while still giving it good offensive prowess + toxic immunity. The set is listed below. Anyways, great team and hope I helped!
Politoed (F) @ Chesto Berry
EVs: 160 HP / 252 SAtk / 96 Spd
Modest Nature (+SAtk, -Atk)
- Hydro Pump
- Ice Beam
- Hidden Power [Grass]