I dont have much experience with pattern making, but here are some tips i learned from others.
Since you’ve already made this ball before, you will have to make a second one.
While working, you have to write down everything you do. Even the hook size and yarn you use.
At the end of making a row write down what you did, at first it will just be messy notes. Make sure to take lots of pictures while you’re working. Especially after each section is made and during the sewing stage.
When you finish, you will take your notes and write them into a pattern. I recommend looking up what standard crochet terms are. So instead of writing single crochet, youd write sc.
When you finish, you’ll have to make your project 1 more time to make sure there are no errors. If your 2 balls dont look the same, you need to adjust the pattern.
When you think everything is perfect, you will take a bunch of nice pictures of the finished product and use it as the cover.
In your description you could write what game its from, and add somethings you think would grab people’s attention.
For the measurements, you can just take a ruler and see how big your ball came out, make sure to write what size yarn you used. This is so people can know if they want to make it bigger or smaller with different yarn types.
When typing the pattern into ribblr, you will see a tutorial section, it will explain how to add your pattern.
Make sure you put in the pictures that you took while making the ball
Since this looks like a bunch of pieces, you should do an assembly section for sewing. Explain where all the sections go. if the placement is important, you should also write what row and how many stitches apart each piece is, and provide photos.
Thats everything I could think of.