Turn timer running? Let the Pokemon Showdown calculator pick.

You already know how to read a damage calc. This one reads the board each turn, picks the move and comes with a Gen 9 OU or VGC team.

OK, pick my moves

Pick OU or VGC next, pass one quick check, then Add to Chrome.

Four moves, a timer, and a foe whose set you half remember.

The calc reads both sides and rolls damage for every move.

It marks the move with the best KO chance before you click.

Your team pack, based on top usage stats, is already loaded.

Calculating a turn on the ladder: which way to use

Best way

A calc that picks the move for you

It runs the damage calc on the live board every turn and marks the move, so the timer is no longer the problem. It can also queue your next ladder game.

The team pack comes from the top usage stats of the format you choose: Gen 9 OU singles, or VGC doubles where you bring six and pick four.

Also fine

A calc synced into the battle screen

You still read every roll and choose yourself. Good for players who want the numbers in front of them.

Skip if the timer is on

A separate calc tab, filled by hand

Setting EVs, items and boosts for every turn costs the seconds you need. Keep it for team building.

Why it lives in your browser

Pokémon Showdown is a fan-made battle simulator hosted as a web application
Source: Wikipedia
So the helper sits in the same browser, installed like any Chrome extension.

Still deciding?

See the turn again

Admit one: a ladder session with the move picked each turn

Gen 9 OU or VGC team included, ready in Chrome.

OK, pick my moves