I've seen a couple good teams end up at around 1440 on PO with up to 5 Choiced Pokes. But for this team, I agree. To alleviate this problem, maybe try a Life Orb/Expert Belt set on Genesect?
It is best to have 1 or at the most 2 choiced Pokemon, or else you will keep switching in and out, and possibly rake in hazard damage.
Another thing, you need descriptions for each Pokemon.
Genesect @ Life Orb/Expert Belt
Modest/Timid Nature (I'd use Modest, as the set runs Rock Polish)
EVs: 252 SpA / 4 SpD / 252 Spe
- Rock Polish
- Bug Buzz / Flamethrower
- Ice Beam
- Giga Drain / Thunderbolt / Flamethrower
At sevensevens's suggestion, I switched out my Scarfed Genesect for this, using a Modest Nature, Life Orb and Rock Polish, Ice Beam, Giga Drain and Flamethrower, albeit with a different EV spread. It has done much better than my old Scarfed one for two reasons: I can switch moves while retaining respectable power and it has a reliable form of recovery in Giga Drain. It's a very straightforward set in that you Rock Polish and start attacking. Giga Drain is for when the LO recoil drops you low. Ice Beam and Flamethrower get nice coverage and handle a lot of major threats. Giga Drain would also somewhat alleviate your Rotom problem.
"Whether Castform the Weather Pokemon can weather the weather is dependent on whether the weather that it's weathering is the proper weather for it to weather. Whether the opponent can weather the weather is also subject to whether the weather that it's weathering is the right weather to weather. Whether Castform can weather the opponent is once again dictated by the weather and whether that weather is the favorable weather for weathering. But most importantly, you should know whether there will be weather to weather rather than what weather they will be weathering and whether they can weather that weather."
- Smogon's Castform analysis