I'd like to suggest couple of things.
Firstly, you have a greninja which probably should do the role of "Taking out ghosts and psychics" single handedly with dark pulse. If you insist on having either dark or ghost type for that role as special attacker, I could suggest hydreigon . ( If you access to that. If not, zoroark is your best option.)
If you dont insist it to be a special attacker and break your team's balance, weavile is by far your best choice, because it also provides ice coverage which will give you great time versus dragons and flyings ( Because you dont have coverage for that and excadrill wont be enough). It is also way too fast and can trap things with pursuit.
Other thing is, using accuracy boost items on excadrill somewhat wasting the item slot considering the fact that wide lens on excadrill will only boost the rock slide and it is not even worth boosting because it is not your STAB move. Also as I stated above, its not enough as rock coverage. You could either give lifeorb / plates to boost their attacks and make it more powerful that way.
As for blaziken, you could get high jump kick and flare blitz via heart scales from onyx ward and make it even more powerful, because just like excadrill, the BP's of those moves arent good enough to be boosted, it is a waste of item slot.
Another thing is, your gengar could do significant damage if you went with team aqua sidequest line which will give you a choice specs, which causes gengar to hit like a truck and eliminate targets easily.