Hi there, I got your request!
So the problem with this team is that it really struggles against fast threats like Mega Aerodactyl and Hawlucha and is weak to Stealth Rock as well. To fix this,
Mew would be an excellent support Pokemon. Mew can take both of the aformentioned Pokemon on just fine and is capable of spreading paralysis, something that your team really likes. Furthermore, Mew can use Defog and rid your field of Stealth Rock. Here is the proposed set:
Mew @ Leftovers | Synchronize
252 HP / 252 Def / 4 Spe | Bold
Defog | Roost | Thunder Wave | Psyshock
Mew should be replacing Raikou, because this gen, SubCM Raikou finds very few opportunities to set up unfortunately.
Now because you have Defog, a suicide lead isn't very ideal, so I suggest
Nidoqueen > Aerodactyl. While Nidoqueen loses out on guaranteed SR, it is bulky enough to almost always get them up, and also has an excellent offensive presence that suits your team very well. Here is the set:
Nidoqueen @ Black Sludge
168 HP / 252 SpA / 88 Spe | Modest
Stealth Rock | Earth Power | Sludge Wave | Ice Beam
The Speed EVs are enough to outspeed 252 Crawdaunt btw.
In this defensive metagame,
Swords Dance Heracross makes for an excellent wallbreaker that can get past Reuniclus, which is currently one of the best Pokemon in UU. MoxieCross is unfortunately too weak without a boost, and you already have a Scarfer in Chandelure, so you're not missing out on much. Furthermore, Heracross gives you a status absorber as well, which is always nice to have. Here is the set:
Heracross @ Flame Orb / Toxic Orb / Leftovers (you can choose which one you want) | Guts
112 HP / 252 Atk / 144 | Adamant
Swords Dance | Close Combat | Megahorn | Stone Edge
The Speed EVs are enough to outspeed 252 Honchkrow as well as all defensive pixies (Jirachi, Celebi, and Mew).
A Choice Scarf Pokemon should always have 252+ EVs and nature in order to be as fast as possible, so I would recommend making Chandelure's EV spread
252 SpA / 4 SpD / 252 Spe with a Timid nature. Also, I would much rather have
Infiltrator as the ability to be able to beat out Substitute users such as SubSD Heracross and even Substitute Zygarde granted it's weakened enough, and Snorlax and Porygon2 are nowhere near as common as they once were, so Flame Body is pretty much useless.
The last change I wanna make is Kingdra's set. You yourself said that Kingdra can offer much more to your team, and I couldn't agree more. Thanks to the new mechanics Focus Energy + Scope Lens gives you a 100% crit chance, and thanks to Kingdra's Sniper ability and STAB Draco Meteor (crits bypass its -2 SpA drop!), it is one of the best abusers of it. This set is a much better wallbreaker than Rain Dance imo, and it also doesn't weaken Chandelure's main STAB. Here it is:
Kingdra @ Scope Lens | Sniper
252 SpA / 4 SpD / 252 Spe | Timid
Focus Energy | Draco Meteor | Hydro Pump | Surf
I'm sorry if this rate was a bit on the long side, but it is what I think to be the best for your team. Hope I helped and good luck with your team
Rob. ^.^