[REQUEST] New to battling, need some help please!

[Civilpsycho]

Hello or should I say Alola. I'm new to online/comp battling but I would love to get into it. Yet there is an impossible to miss mountain in front of me, between natures, IV EV and what Pokemon are good for what roles (and what roles I should have in a team) I'm lost. So this is a simple cry for help from the players more accustomed to the ways of comp. any and all help is welcome. I currently have a short list of my current favourites in Alola and I think that would be the best place to start. 
My current short list is 
Salazzle 
toxapex
Vikavolt
Tsareena
Beware
Lurantis
Marowak (Alola form)
Muk (Alola form)
Golisopod
Lycanroc (midnight form)
Mimikyu
Araquanid
Palossand 

To make it clear I'm playing Pokemon moon, and I'm not looking to go to any major tournament or any thing like that, I'd just like to make a decent battle ready team.

[Marcusube]

Well then, welcome to competitive battling. The easiest way to determine natures is to look for the highest stat that the Pokemon has so for example with Salazzle, it's highest stat is it's speed stat so you would want to go for a nature that increases speed, however, since Salazzle is a special attacker, you want to run a Timid nature

For defensively oriented Pokemon like Toxapex, however, it can be a little tricky. To be honest in most situations it comes down to preference whether you prefer your Pokemon to take special hits better or physical hits. I say in most cases because there are going to be some cases where only a specific variant works for your team

A formula I like to use for team building is: 0-1 Sweepers, 1-2 Breakers, 1 Stallbreaker, 2-3 Pivots or Walls, 1 SR setter, 1 Hazard Remover

If you don't understand what these terms mean, check out here

Best of luck to ya!