N i k o, Spirit of the Wolf, Twilight_Kiryu_ and Darkest Soul all have minions but they're all not fully happy. Why is this? :( I thought that minions were supposed to help keep your pet(s) fully happy! :(

That randomly happens sometimes. A couple of Pets on my account aren't full happy either at the moment and in the past that even happened to me with Pets that had Minions and were in the Veta Lake Resort were Pets not only receive food but also entertainment. It should fix itself after a while so it's nothing to worry about.

Same. A trip to Veta Lake always gets them in full food and entertainment stats :) You could always buy toys, but there aren't really any penalties having an unhappy pet for a little while, so nothing to worry about :)