This site is intended to help with mastering PvP in Pokemon Go. It covers the best picks for all three leagues (Great, Ultra, Master).
Use the navigation menu at the top to access different pages with useful information.
There are 4 components to winning in PvP in Pokemon Go:
1) Team composition
2) Pokemon switching
3) Shield management
4) Charge energy management
1. Team composition
There are 3 parameters that matter when selecting pokemon for your team:
1) Pokemon type - determines its defenses, what types of attacks it will be strong or weak against.
2) Pokemon attacks - determines its offense, what types of pokemon it will be strong or weak against.
3) Pokemon stats - determines the attack, defense and health of the pokemon, making it overall stronger or weaker.
2. Pokemon switching
Switch your pokemon if it's ineffective against the current opposing pokemon.
It's also a good idea to switch a pokemon with an already charged move, so that it can use the charge attack right after switching back, surprising the opponent. Unpredictability is your best friend.
3. Shield management
Try to use shields as late as possible, after seeing all opponents pokemon and figuring a strategy of dealing with them.
Or use it all on your first pokemon, but only if the opponents is also using their shields.
4. Charge energy management
Sometimes it's good to not immediately use a charge move when you get enough energy. If the opposing pokemon can't considerably damage yours - save the charge move for the next pokemon.