While it’s compulsory to complete each region’s Rescue Quest to progress in Creatures of Ava, that doesn’t mean you should ship off every creature you find in any old Rescue Bot. Every species has a purpose and a willingness to help—it’s up to you to make use of them.
Here are all species you can tame in Creatures of Ava, including their abilities, the difficulty to tame them, and the threat to Ava when infected with Withering.