Transition animation with 2D sprites in 3D game with rotating camera

If I want to use 2D sprites in my 3D game, and let's say that I have all the animations for my character from 4 different angles: from the left, right, behind, and in front of. So if the camera rotates around this object that has a 2D sprite, the idle stance should switch from the front view, to the side, to the back, to the other side, right? But what do I do about animations? I assume that I don't have to use some incredibly complex Animator object with like a million transitions. Is there any tutorial on how to do this the right way? Maybe to grab the exact frame of animation that is currently playing, but then switch to a different animation at that exact frame number? I'm sure this has been done before...

Anyway, thanks in advance for your help!