Delphox: Change Fire Blast to Flamethrower for obvious reasons said before. Also change Shadow Ball to Reflect. Your team doesn't really have a pokemon that can take physical hits, so I think it may help you. Keep Magician. You can steal really good items in important battles.
Leavanny: Get Swarm. Everything else is pretty perfect.
Heliolisk: Get Glare instead of Thunder Wave because Glare isn't an electric type move so it hits ground types. Also looking at your team getting Rain Dance instead of Dark Pulse may also be an option.
Dragalge: Instead of Toxic, Get Trick Room, because is Reuniclus can't set up Trick Room for whatever reason, your whole strategy goes down the drain. Also get Surf instead of Hydro Pump for reasons said before once again.
Reuniclus: Signal Beam instead of Grass Knot.
Clawitzer: Absolutely perfect.
One note: Give all your pokemon speed decreasing natures unless they have good speed because then Trick Room will allow you to outspeed other pokemon with Trick Room active. It may backfire, though, but it's just a thought.