I use Mimikyu as my visual and chance to set up, depending on their pokemon I'll choose between offense or defense. Mimikyu will use Baby Doll Eyes and Shadow Sneak if I feel threatened. Copycat if they have additional stat moves or their own weakness. Mimikyu had focus sash not realizing originally. I'll use Gyarados if I know their team is easily taken out using Moxie and Life Orb. I use Rain and/or Dragon Dance if I know I have the opportunity. In doubles I'll pair Hateena with Gyarados because she uses Life Dew has been pretty sturdy in doubles
I use dragapult for speed and snorlax if I see I'll need a fighting chance with the opponents team or they have a lot of ghost type. That seems to have been popular.
As for items, Dragapult has choice scarf. I can't remember the others off hand. I didn't have a lot. One has heavy boots because I know ferrothorn has been popular too with traps.
Okay..from what your telling me its a mix match of muddled strategies and roster as well as just a general lack of experience. What I mean specifically is lets take what you said about Mimikyu. Mimikyu is much,
MUCH more threatening using it disguise ability to get off a Swords Dance vs Baby Doll Eyes. The opponent can also switch out their pokes at anytime to get rid of stat debuffs like that, vs your Swords Dance where your the one in the drivers seat.
Mimikyu@Life Orb
Adamant/Jolly
252 atk, 252 spe, 4 SpD
-Swords Dance
-Shadow Sneak
-Shadow Claw
-Play Rough
This is not only the standard yet more threatening Mimikyu set, but its also how we share our pokes online to be "rated" by other battlers. Listing all your pokes in this format makes it much easier for people online to observe your team more closely.
To be honest, I think the best advice I can give for you is probably just to keep on battling, even if you do lose. Back when I first started in Diamond and Pearl it was the same thing. Getting into pokemon where it feels like everybody else makes the right decisions, has the pokes with answers to yours all the time, and it feels like its just impossible to win. However, while many other forums will say "learn from your losses" as a blanket statement to that, and its not untrue, the more valuable piece of the puzzle your picking up here is
Experience. Its the best teacher afterall, and noticing what you DO lose to and strats other people use, eventually you start to not only adapt those strategies and better them, eventually you'll soon come to realize many people are unoriginal, use the same strats, and a majority of people you will face there was never anything to fear in the first place.
Just don't get disheartened and give up. Its fine if you lose 10 or even 20 times in a row, its only when we quit the game were trying to get better at do we truly lose.
Anyway outside of that, more specific advice: Natures are extremely important, Jolly vs Adamant Gyarados is a big deal since Jolly outspeeds more pokes then Adamant does, but loses some dmg that Adamant gets in some places. I think a good fit for you is a "balanced" team.
I do have to ask since you mentioned you did it in another post- Is this a doubles or singles team? Very important to know since major strategies are different for each.