Do you need "an-otter" companion? If you remember my otter OC Tazer, I can volunteer him to be new-blood part of the crew. Heck, I'll even draw a ref sheet of him in your style & you can do whatever you with him. He would just a normal cartoon otter wearing a black backward ball-cap and a plain blue shirt with a simple white lightening bolt on front. I would love to help you for the story.

Axolotyl? Red panda? A BEE?!

Under-rated animals? Hmmmm.... You don't see many voles, shrews, ardwolves, wombats, suger-glidders, horse-shoe bats, leopard seals, Darwin-frogs, nightscretches, alligator bugs, blind-cave-salamanders, soles (type of flounder), or camens these days. You could try using the animals above if you wanted to.

Also, I've always noticed that there always is a certain formula to the creation of a team (the hero, the best friend to the hero, the old guy, the smart guy, the tough guy, the token kid, the team pet or mascot or robot, and the token girl on the team). You could follow this old cliche-formula if you wanted to, just for fun....

Venus Flytrap. Why not.

Sloth or armadillo? They're pretty underated, right?

How about a tapeworm, bot fly, silverfish (the insect), scorpion, vinegaroon, cicada, spider, horseshoe crab, or sea spider(they aren't arachnids, but are related to them).

@Larka Leopard seals ftw! Also the leopard seal should be a protagonist since they're always portrayed negatively.