Having recently got into pokemon PVP for the first time in many many many years It has been a learning experience due to combination of gen5 pokes, some gen6 movesets, some gen 9? and as you said, a deficit of information available.
I found some pokepaste's within these forums and some were good, others not so much, a key learning source for me has been AFC Adinho's youtube channel, observing his team, move coverage and commentary.
Moving on from this, I started with a rain team and just went into OU until i won my first Pokemon from rewards, doing this i got an idea of general team comps, play styles, meta mon etc.
Utilizing smogon on both B/W and S/S, along with Marriland and ingame to see commonly paired pokemon, I selected my preferred pokemon to use, built some theoretical teams using smogon/ingame and checked the coverage with marriland, I then rebuilt these teams on showdown and had a few test fights with my son to see if i liked them at which point I've started building them.
I know this isn't much help but it's just have I've managed to get established