Here’s what I came up with.
Delta Charizard:
I’d keep it the same. Your team has no ice coverage besides Frost Breath.
Breloom:
Mach Punch over Toxic. Breloom isn’t that fast so priority is nice. Imo, it’s not fast or bulky enough to really make use of Toxic. And you already have Spore. I put Toxic on another 'mon.
I don’t know if you can get Superpower, but I like Superpower more than Drain Punch. Technician Breloom with Bullet Seed would be ideal, but I think you can only get that by breeding.
Bronzong (replaced Aggron)
Imo, Aggron is bad, so I put Bronzong in its place. Bronzong is nice because it patches up a ton of weaknesses on your team, avoiding Ground-type attacks with Levitate. It also has much more balanced defenses at the cost of some offensive potential.
Moveset:
Flash Cannon/Iron Head/Gyro Ball/Heavy Slam
Psychic/Zen Headbutt
Toxic
Rock Slide/Trick Room
Bronzong has more Att than SpA, so physical is probably the better choice. Iron Head is the most consistent out of the Steel STABs it gets, so I’d probably go with that. Since the Tapus aren’t in this game and no one’s using Xerneas, I’d say there’s probably no need for Gyro Ball or Heavy Slam. Bronzong is super bulky so Toxic is good. Rock Slide is for coverage. Trick Room will pretty much guarantee that Bronzong goes first, but it screws with the rest of your team. More specifically, I was thinking Trick Room (and Bronzong in general) screws with that one E4 member who relies on Trick Room.
Manectric
Thunderbolt and Flamethrower are great, Electric Terrain is meh (I personally wouldn’t use it), and Charge kinda sucks. Electric Terrain also prevents Breloom from putting things to sleep. The three moves I came up that would be helpful are Volt Switch (I don’t know if it’s available but if it is I highly highly recommend it), Snarl, and Thunder Wave. You can keep Electric Terrain if you want but Charge should be replaced for sure.
Houndoom
Patches a couple weaknesses in the team, most notably Ghost. Flash Fire is the best ability.
Moveset:
Flamethrower
Dark Pulse (iirc this is in one of the Void Gauntlet places? I know it’s somewhere and you probably have it)
The last two slots are between Will-o-Wisp, Snarl (not if you put it on Manectric), Nasty Plot, Sunny Day, and Solar Beam (obviously only with Sunny Day).
Not much to say, it’s a decent attacker with the ability to cripple opponents with Snarl and Will-o-Wisp and set-up potential with Nasty Plot and Sunny Day.
Staraptor
Provides immunity to Ghost and Ground, which is nice. Intimidate is a superb ability and I would recommend you use it. You could also use Reckless to boost the power of some attacks. I have to reiterate that although Reckless is good on Staraptor, Intimidate is far better.
Moveset:
Brave Bird
Return (make sure to get that happiness up)/Double-Edge (if you use Reckless)
Close Combat
Endeavor/Quick Attack/U-turn/Final Gambit
Staraptor is amazing. It’s fast and hits like a truck. Intimidate, Final Gambit (might screw with happiness though), and Endeavor are extremely crippling to opponents. U-turn and Intimidate make Staraptor a great pivot (I don’t know if you can get the TM though), and Quick Attack provides STAB priority. It provides two important immunities your team needs. And unlike most Flying-types, it can’t be walled by Rock or Steel-types because it gets access to Close Combat. Truly, this thing is great.
Here’s a link to the team with a chart of type resistances and weaknesses: http://www.teammagma.net/teambuilder/?487|286|437|310|229|398
Girantina replaces Charizard because it has the same typing.
You can see that there are two weaknesses left on the team. Ice hits 3 for super effective and Fairy hits two with only one resistance. This isn’t a huge problem though. Manectric and Breloom deal with any Water-types that carry Ice moves, and Bronzong walls and slaughters Ice and Fairy-types (do be wary of Shadow Ball from Gardevoir and Sylveon).
For some reason I couldn’t get the moves to carry over, so you won’t see the type coverage your team has, so I’ll just tell you in this reply. You’re missing Ground, Rock (if you don’t use Rock Slide on Bronzong, but I think TR is better), Bug, Poison, Fairy, and Water. Bug, Rock, and Poison aren’t very helpful (Poison especially because there are not Tapus in the game). The only thing Ground hits that your team doesn’t is Fire. I don’t think this is a huge issue because Charizard resists it and Houndoom absorbs Fire with its ability. Missing Water coverage isn’t too bad because your team already hits everything that Water does.
One thing that could be problematic is the lack of Fairy and Ice moves. Your only way of hitting Dragons is with Charizard, which is not ideal because Charizard is weak to dragon itself. My recommendation is to see if you have HP Ice/Fairy/Dragon on Manectric or Houndoom. Since there’s a good chance you don’t, you just have to play around Dragons by using Staraptors Intimidate, Bronzong’s typing (almost all Dragons have Fire and Ground coverage, but with abilities, you will be able to take minimal damage from/be immune to one of them), Houndoom/Manectric’s Snarl, and status conditions.
I don’t really have anything else to say. I hope I was helpful and good luck on the E4.