I just got a mystical donadak plushie but can't seem to do anything with it when clicking on it, there's no other options than to put in a shop/plushie collection. I only have 14 pets. What am I doing wrong, or can the plushie not be used for that anymore?

believe that option stopped when they changed how the pet slots worked

No, the mystical plushies no longer give pet slots. They're just collection items.

You can buy pet slots for CSC directly through the pets page: url=https://subeta.net/pets.php?act=buy_slots[/url] or for sP through the Millionaire Center: url=https://subeta.net/ss.php/millionaire#/shop/Pet_Slots[/url] up to the limits listed on the User Dashboard (a total of 65 CSC slots from the pet slot plushies and early totems (soft max 10) category and the new slot additions category, and 25 from the MC ranging from 20 to 200m sP)