The first thing you gotta know is that Pokémon Go battling is sorted into leagues. When you challenge another trainer, you decide ahead of time which league's rules you'll fight under.
Different leagues have different caps on the strength of the Pokémon you can use to battle. The highest-level league, the Master League, takes off (almost) all the limits: You can use any Pokémon, at any level, including so-called Legendaries.
The one caveat are that you can't use Ditto or Shedinja, two weird cases in the larger Pokémon canon, in any kind of player-versus-player battles, including Master League.
If you want to battle another trainer, you'll use your phone's camera to scan their unique QR code. You'll only be able to battle remotely with your Ultra Friends and Best Friends, as a perk for IRL besties.
Niantic says this is to encourage face-to-face interactions: It envisions Pokémon Go players getting into rumbles in parks, malls, and anywhere else Pokémon trainers might gather.
You'll face off with the other trainer, giving you a chance to pick your team of three Pokémon (and show off your character's outfit).
Now, it's time to throw down. Pokémon fight one-at-a-time, swapping on the fly to best match their Pokémon's strengths to their opponent's weakness. If all three of your Pokémon get knocked out, you lose.
Of note is that the original Pokémon games for Nintendo's video game consoles have always featured teams of six. Niantic says that this makes fights go faster and keep moving, which is better-suited for a smartphone game like Pokémon Go.
But you might notice that this looks a little different from the regular Pokémon Go battle screen. That's because these battles work a little differently. You'll still tap the screen to do your basic attack, chipping away at your opponent's health.
...but now, every single Pokémon can learn a second charged move, in a first for the game. This little change could add a lot of strategy to the game.
Note that Salamence here can have both water and fire-type attacks in the tank now, making it that much more effective — and that much harder to defeat in combat. This, alone, stands to shake up the conventional wisdom in terms of Pokémon Go strategy.
You'll need to spend some Pokémon candy and a little Stardust to get the second charged move. Once you have it, though, you'll be able to use it in other game modes.
Note that just like before, some attacks take longer to charge up than others.
Also new is that you can charge up your attacks further by tapping rhythmically on the screen. Keep tapping, and your attack will get stronger.
This leads to another new mechanic: Meet the "Protect Shield." When an opposing Pokémon launches a charged attack your way, you have the option to either absorb the hit, or put up one of your limited number of Protect Shields.
It's a guessing game. You can use a Protect Shield if you're worried your opponent has a super effective move that could finish you off. If you're wrong, though, and their attack was something you could have shrugged off, you're down a shield.
To the victor go the spoils. Niantic says that you'll earn rewards for the first three times you battle in a given day, though you can battle indefinitely just for fun. The rewards include the hard-to-find Sinnoh Stone item, as well as the Stardust you need to make your Pokémon more powerful.
The availability of the Sinnoh Stone as a reward should come as a relief to frustrated players, who can currently get it only as a random prize for completing a seven-day streak of Field Research tasks.
Also of note is that winners and losers both get some prizes, as a way to make sure even lower-level players get something from the experience, Niantic says.
Finally, you'll be able to fight Candela, Blanche, and Spark, the AI-controlled leaders of the game's three teams. This is good practice for players who want to ease into fighting their fellow humans, and you'll get some rewards, too.
This also comes with some very good news for Pokémon Go obsessives: Fighting the AI-controlled team leaders will earn you progress towards the Ace Trainer in-game achievement. This is notable because the last time Niantic updated the game's battle system, the changes frustrated many people by making it impossible to complete Ace Trainer.
