Beasts are the real game changers because of their high health and damage. When you build the Beast Cave you can select 1 beast. When you build the Beast Keeper you will be able to select and raise the other beasts. You can command one beast at the time, but you can change between them in the Beast Keeper . You can raise your beast up to level 6 by training it daily.
Only the Wom-Kong needs to be unlocked differently.