Okay, from me thinking about what forms the Rift Engine Adventurers are, I had finally figured out what they are:
Dipper's form in The Lion King, or other animal morphic dimensions is him as a Hawk, and a half mouse and half rat.
Shadow's form is a Road Runner, and a mouse.
Dottie is normal.
The Penguins are normal too.
Pete is a dog, and a mouse.
And Hank is a wolf, and a mouse.
That's all I needed to say what forms they change into from animal dimensions. Cheers.