Good specialist?

Hi guys, I need more advice. What are some good specialists that I can add/create for my team?

Tank types:

I am using a Stegotops and Bouldon as meat shield. They are so useful I am thinking of adding another one. I have a baby whale/mammoth/rhino… which one is the best?

Also, I am looking for a metallo, so I will add him later.

Healing:

I have lots and lots of Halocats. And I am looking for chubs(?)

Magic/Stun:

I have a dark witch cat that’s useful. And lots and lots of electric foxes and a Hindu god siting in a cloud. I also have lots and lots of nitroxide-birds that I only use for boss battles. 

Most of my monsters are attack types, but I should diversify a bit for strategies to make the game more fun. I am at the snowy land right now (about 3/4 through the game?).

I’m not the most patient person, so I am not going to farm for egg-dragons/starters. But could you guys suggests some good semi-rare monster that I should add to my team?