I found the other pixpet-by-color guides really helpful, so I created a sheet to help keep track of my pixpals too. The first page shows all of the possible pixpals by color and rarity. The second two pages are different versions of checklists: in the first you can just copy and paste the colored cells from the first page once you hatch them, and in the second you can clear the cells as you hatch them.

Feel free to make a copy of the sheet and record your own pixpaldex!

Let me know if you catch any typos, or if there's other useful information that I should include.

Here's the link!