To begin, take a Showdown export to add a team. The export usually looks like this:
OR, if you already have one, import a JSON via "Load Draft" to continue working on an existing document.
Calcs
Each Pokémon on your team can contain both offensive and defensive calcs. You can also add small notes, such as what your Pokémon outspeeds.
Matchups
Add a matchup with a title and potentially a paste for easy access within the same document. You can also add multiple matchups.
Complete Gameplan 1 with text and a composition.
You can add alternative gameplans.
In each gameplan, you can add Pokémon Showdown Replays.
Draft
If you haven't finished your document, you can save it as a draft. You will receive a JSON containing your work, which can be reused on the homepage by selecting "Load Draft".
Save and Send
By clicking "Save," you will be taken to the visual page of your document.
You can share it, edit the document, or download the corresponding JSON document (also allowing you to modify it as you wish before re-uploading it).
Save Locally
If you don't want to make your document public, you can "Save Locally". (Only one document can be saved locally at a time.)
You'll be able to access it with the "View Local Doc" button, or by clicking here.
This will allow you to visualize your document without sharing it with others, thanks to the data stored in your web browser. However, your document will not be available in other web browsers or devices, unless you Save Locally everywhere you want to access it.
If you clear your browser data, you will lose your document.
Best method to Save Locally & Share
While not being the most user-friendly method, the best way to save your document locally and share it with others is to:
After saving your document locally, download the JSON file.
Send the JSON file to the person you want to share your document with.
They can then load and save the JSON file to Matchups.net by clicking "Load Draft" then "Save Locally".