Please write below every member the role they play for the team, because right now it just seems like a gather-up of powerful individuals, with zero co-operation. Find what each pokemon does, and you'll know soon how to build around certain cores in your team.
Edit: Ok I made a few changes to your team, trying to keep the format as similar as I could.
Ok who am I kidding? I turned this into a total speed control team... and it's quite nice, so kudos me!
First, I changed your mega. M-Heracross does the same thing Crustle and Scolipede did in this team, so I got you a Pinsir with CC, Return, SD in case you need to wallbreak or when you force a switch, and Feint (which you can swap for Quick Attack) for priority since 105 base speed is not the best in the tier given that everyone and their mother will set up on you, given the chance.
Then I turned your Galvantula into a lead set with Sticky Web, Thunder, Bug Buzz and HP-ice for maximum coverage. It now holds a sash, so you'll have the opportunity to set up your webs anytime. Galvantula is a scary glass cannon which can be used late game for sweeping too. Web gives you multiple opportunities to set up or attack back with your pseudo bolt/beam coverage.
Next comes Volcarona. This one needs to become a wallbreaker, so I changed it completely. Ok I kept Quiver Dance, but you expected that, right?
Now it has Fire Blast, HP-ground and Giga Drain for maximum longevity, given it can set up on Rotom's face when it has a Passho Berry. Yep, a good, all rounded win-con.
At this point I realised that Yanmega is completely redundant, so I euthanized it, and put Forretress in its position. Now you have a good defensive pokemon that can spin the hazards away, set some on its own, use gyro ball for good damage even with no Atk investment, and do a slow volt switch into something you want to set up with or wallbreak without having to worry for damage while switching in.
I didn't like your Crustle so I made it hold Knock Off. Sue me. I also tossed Stone Miss and gave it something more reliable: Rock Slide. This way, as soon as you set up, you won't have to worry for misses all the time, besides you don't really need the extra power. Knock off helps get lefties and eviolites out of the game. Plus, nobody expects it. Yay?
I also tossed Rock Slide from Scolipede and sub'd it with Protect. Trust me, when the opposing scarfer knocks at your door, you'll love this change.
Here's a replay that pretty much shows what most pokemon can do now
http://replay.pokemonshowdown.com/monotype-337686024
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