I wouldn’t change too much if it’s already working well. Alakazam makes sense here, especially when Trick Room would otherwise give the team trouble. Imprison blocking Protect and Expanding Force as well is pretty useful.
The first thing I’d try is Protect on Blastoise over Aura Sphere. Sneasler already gives you Fighting coverage, and keeping Blastoise healthy while you set Tailwind or deal with a threat should help you get more out of Water Spout.
I’d also try Life Orb on Gholdengo. With that much investment in Special Attack and Speed, I’d rather give it the extra damage straight away. Poison Barb on Sneasler is another option for more consistent Dire Claw damage, since Scope Lens doesn’t increase its chance of inflicting status.
If Alakazam really only comes out for Imprison, Focus Sash could be worth trying over its Mega Stone. That lets you bring it alongside Mega Blastoise without having to choose which one gets to Mega Evolve. You’d lose the Mega’s extra Speed and damage, though, so it depends how often those matter.
Choice Scarf Ditto is worth a few games too. It copies the opponent’s Speed when it transforms, so Scarf helps it move first instead of potentially speed tying. Being locked into one move can be awkward in doubles, so that one’s more of a preference.
I’d keep Aerodactyl for now. Tailwind and Wide Guard both do a lot for this team. Start with Protect on Blastoise and the item changes, then see how it feels before replacing any Pokémon.