It'd make more sense if you actually gave us details such as each Pokemon's abilities and natures so we can help. For example, a Water Absorb Politoed works different than a Drizzle Politoed and a Rough Skin Sharpedo is virtually useless especially in comparison to a Speed Boost one. Natures matter so you can determine if you want the Pokemon to be physically or specially defensive/offensive
I need to capture 2 of the members, but I think I will hunt them down tomorrow. The corphish is a pain to get, because it is a shiny team and it's hidden ability is super rare. About them more info when I get them. These members where a planning, and they aren't trained yet. For the members I have:
Milotic:
Marvel scale, calm nature, has a fantastic stat in speed.
Gyarados:
Intimidate, docile nature, has a defenitly good stat in defence.
Politoed:
Damp, timid nature, has a fantastic stat in attack.
Are these any good? I will let the other members know as soon as possible.
Alright what you can do is run a physically defensive Milotic with max HP and Defense (this would've been more ideal with a Bold Nature but Calm can work as well). Scald, Dragon Tail, Toxic and Recover for moves and run it with the Leftovers
Throw a mega stone on Gyarados and run Dragon Dance, Substitute/Earthquake, Crunch and Waterfall with max attack and speed
As for Politoed, you can be gimmicky and run a Life Orb Politoed with Hydro Pump/Scald, Ice Beam, Focus Blast and either Psychic or Toxic. If your Politoed happens to have Hidden Power Ice/Grass you can run that over Psychic for better coverage. Also try to grind Battle Maison for an Ability Capsule to switch Politoed's ability to Water Absorb
These are just sets I can suggest with what you have. If they had egg moves (eg Haze Milotic or Encore Politoed) then they could run those moves as well.
My Octillery has sniper and his moveset is focus energy, ice beam, water pulse and signal beam. I thoughed ik was a great pokemon for breaking physical walls, because crits get very easy to get and very powerfull. Does this strategy work?