in addition to vileplume, flareon or CAMERUPT could give you tons of shit with mixed sets. i could see opposing pinsirs giving you trouble, and nidoking. cm misdreavus seems like it could be a pain. feraligatr seems like your worst nightmare. i realize it's a bit hard to keep things like offensive variety and synergy in mind when you're going for monocolor, but i think your pokemon, though individually some of the best pokemon in the tier, overlap in their offensive and defensive roles a bit too much, and the team is ultimately a bit too passive, and not focused. you haven't really committed enough to an offensive or defensive goal. a lot of the team is quite slow and nothing can sweep without setup. meanwhile, all of your tanks are trying to be sweepers and you don't have much support for them. you know quagsire is dead weight offensively. you know lanturn isn't scary without a cm. you know muk isn't sticking around too long to do additional damage before it has to explode. omastar is horrifying with a cm, but without one it's not scary enough offensively nor is it lasting long enough for all it has to accomplish defensively i think. pinsir is immense if you get the swords dance in at the right time. against certain threats like electabuzz or tentacruel this team might seem impenetrable, but for all of the tanks it has it sure has a lot of weaknesses. without wish support or rest here and there your tanks probably won't do enough offensively or defensively to really be worth it.
i would think about using restalk muk, or maybe (shiny!) hypno over either lanturn or lunatone depending on the role you want it to play (cm or support) or where you want the team to go; maybe gligar over quagsire. you could use sharpedo, manectric (even though it sux) or choice band granbull somewhere for some immediate offense, or use cb (shiny) aggron over omastar for offense, and stuff qwilfish somewhere else (over lanturn?) if you want to keep the spikes. sableye would block spin and make shedinja's life harder as well as shut down kangaskhan. :x i really think lanturn or quagsire or both need to go for something that is going to provide support and/or pick up the slack though. with cursetalk muk can handle electric types and tentacruel on his own, and then you have much more room for offensive and defensive variety.
<&spies> FUCK i just SNEEZED and made a MESS