Is there an item that increases a pet's hunger? I'm trying to feed my Dillema a bunch of food items for achievements, and I was wondering if there was a way to speed up the process.

No items that I know of, but there's the cleansing pools. https://subeta.net/explore/shengui_guo/bathhouse/cleanse.php

Ooh, that's great! Thanks!

[Item=Malerias Clawed Glove] Can curse your pets not in battle to lower hunger to 0. But I haven't tried it yet because I don't have a T6 pet and I think the curse might be broken right now. I saw a thread saying it was a while back.

To clarify: is not broken as far as I know, I've used it very recently. The way it works is that for each turn its used in battle, it can set one of your non-battling pets to a hunger value of 1 randomly.

This means that if I were trying to feed my pet Jhet, I would battle with my pet Imperator, and have another tab open where I can check the hunger status of Jhet. Each turn that I use the glove, I check the other tab to see if the hunger has changed. The reason why I have to do this is because the glove can also feed my pet/make my pet un/happy, so I want to catch when my pet is at 1 hunger and feed it before the status changes again.

Interesting! I don't have any pets that are strong enough to use something of that tier, but that's good to know :m