First, I need to know if this is just for in game or you are going competitive.
So these things that I will mention are good for in game or competitive.
First, your team seems a bit well rounded in terms of typing.
However
Your movesets don't provide much coverage.
Having two or more moves of the same type are usually bad.
On a personal preference, I once did this to go through long paths like Victory Road then I change the movesets once I'm at Ever Grande.
HM moves are also bad for most pokemon with the only exceptions being Surf and Waterfall. Dive, Fly and Dig can be somehow good in game since AIs barely switch but when they do, they do. Drake switched out his Shelgon when my Sceptile used Dig. Against other players, they can just switch out to block it so it's bad.
Get someone to be your HM Assistant for field work. (I feel terrible calling them HM Slaves.)
I'd suggest a movesets like:
Blaziken - Dual Attacker
-Flamethrower/Blaze Kick
-Sky Uppercut
-Bulk Up
-Aerial Ace/Earthquake
Boost your Aerial Ace/Earthquake and Sky Uppercut with Bulk Up. Defense also increases with it. It helps you sweep.
Swellow - Physical Attacker
-Aerial Ace
-Facade
-Steel Wing
-Focus Energy/Quick Attack
With guts, Facade can be a pretty good STAB move. Getting poisoned is your best way to go. Use Focus Energy if you want feel like getting Critical Hits. Use Quick Attack instead if you want to utilize a paralysis and still hit first. It also helps against the Salac Berry + Endure + Reversal/Flail combo. Facade may also work if you can survive the hit. Steel Wing is for coverage.
Mightyena - Annoyer
-Crunch
-Swagger
-Toxic
-Roar
Crunch is STAB. Use Swagger to buy some time to apply Toxic then Roar. Repeat. Just hope that they will hurt themselves with the confusion instead of you. A team with full toxic is easy to take down. Just watch out for abilities like Guts and Synchronize.
Wailord - Special Wall
-Surf
-Ice Beam/Blizzard
-Sleep Talk/Amnesia
-Rest/Rain Dance
Amnesia is for making you more bulky somehow. Rest is for restoring HP. You could try Sleep Talk + Rest Combo as well but it's pretty random.
Wailord's Defenses are pretty low as well as its speed. Watch out for fast hard hitting Pokemon that can OHKO you with an Electric/Grass move. Your HP will help you too, to some extent. On a personal preference, I'd pick Ice Beam over Blizzard because it has better accuracy and more PP.
Finally, Rain Dance works like a five turn Agility for water types and it helps your next Pokemon too.
Manectric - Special Sweeper
-Thunder/Thunderbolt
-Crunch/Bite
-Thunder Wave
-Quick Attack
Thunder/Thunderbolt is the same with Ice Beam/Blizzard but if you have Rain Dance in play, Thunder reaches 100% Accuracy. Thunder Wave is used to cripple while Quick Attack is the same reason as Swellow's to some extent.
Aggron - Physical Wall/Attacker
-Iron Defense/Protect/Double Edge
-Earthquake/Dig
-Rock Tomb/Rock Slide
-Iron Tail
Your moveset is already good. If you feel like replacing Dig with Earthquake, then do it. Rock Tomb is STAB and if you can get Rock Slide, It would be good. The speed reduction with Rock Tomb also helps. Iron Tail is another STAB with low accuracy. Iron Defense makes you more tanky against the frequent Earthquakes and other ground type moves but don't much of it. Protect is also useful if you want to see what move they will use against you. It requires prediction though. Take Double Edge if you want to. Choice Band helps if you don't have Iron Defense/Protect.
Well... I've tried my best to bring out your team's potential without swapping them with others.
