Pets inspired from more animal groups and subgroups. Literally every pet is a vertebrate. And yeah, yeah I know vertebrates are probably more popular but I think theres a lot of space for more varied cool designs. Like many have already said in this thread, underwater creatures have a lot of potential. I would really enjoy an eel based pet (SHH I KNOW IT HAS A SPINE BUT I EELS ARE COOL OK). Arthropods and Mollusks also have a lot of potential, both in and out of water. Crustacean pets, ocotopus/squid pets. Also insects. We have mobath yeah, but we could see more. A really cool combination I'd like to see would be Praying Mantid dragons. But i would understand if these are harder to implement because they clash with the artstyle, or because a lot of people dislike bugs. Oh also, stuff based off inanimate objects. I think a golem would be really cool. I can picture a rocky one with coral and seaweed n stuff on it.

edit: oops i just saw komodo said no insects. i guess my mantid dragon dreams have been crushed. Pun intended.