How on earth do you beat this game...seriously...

I am genuinely stuck. I have given up on playing this game like so many times to just comeback and get my shit kicked in again. How the eff do you beat this game bro. I have played nearly every pokemon main series game so it's not like I'm new to this shit. I am incredibly frustrated and just want to know a good team to freaking beat this game. I have 3 days played and 138 classic runs with no freaking wins. I have made it to the 190-195 multiple times and literally can't even get over the hump to get to eternatus.

Edit: Took some advice, got to level 200. Have been here for an hour. The AI changes what moves in does different orders now? I can't even take note of what is going to come next.

Team:

Skeledirge, Mega Venasaur, Primarina, Toxicroack, Cloyster, Klefki.