I have read the sets you've mentioned however the Politoed and Starmie sets are vital for the team's success and the defensive sets just don't work for me as this is an HO team. Starmie needs all the coverage it can get to remove things that wall Metagross. For Volcarona, it is indeed annoying to have Substitute sometimes. I'll try out Fire Blast however, I won't change the nature as like I stated, the set isn't meant to sweep. Modest grants me the ability to 2HKO TTar with a +1 Bug Buzz and should I run Fire Blast, it will also give me the chance to OHKO Ferrothorn.
Dragonite is the biggest question though. Running Superpower is kinda counter productive to the set since I need the stats that Dragon Dance provides. Having said that Aqua Jet 2HKOes Genesect after Stealth Rock, I might change Waterfall into something else. Any suggestions? I'm open for Earthquake or something else to hit Jirachi and Ferrothorn. I mean with the current set, indeed I am walled by Ferrothorn but I have way too many ways to get rid of it. And I mainly use Dragonite as a late-game sweeper once the walls have been removed or are weakened.
Anyway, if you're still questioning why I choose not to have Recover on Starmie, here's my strategy: I get rid of Stealth Rock users as quick as possible as most of them are threatened by either Metagross or Starmie. The case with Starmie however is different. Once the SR mons are out, I can freely Rapid Spin and bring out my sweepers. Though I respect your opinion (as I find myself in a tough situation without Starmie), I will still choose to run Ice Beam.
EDIT: also on the Genesect part of the Volcarona rate, I don't need to outrun it since at +1 SpD, it can't touch me and I can simply OHKO in return with Hurricane.
If Slaking gets another ability other than Truant(and Slow Start), it would be Uber with that monstrous stats.