How to blend 2d humanoid animations?

I am a real noob on animation blending, especially on 2d. So here are my questions.

What are the requirements to do have nice blending between animations? Do I need bones to properly bend the animations? What are the basics? I can't seem to find a 2d tutorial/example on this. I'd be nice if some can link here.

 

depends on how you are animating.

as of my knowledge, there are 3 ways to animate in 2d.

1. manual scripting. (translate, rotate, etc) but that's why the animation tool was created, don't bother looking into this.
2. using unity's animation in the editor.
3. animating through sprite sheets.

if you want to use unity's blending scripts for 2d, i think you can just make a flat 3d model, rig that one, and animate. i haven't tried doing this myself, but i don't see any reason why it will not work.

 

Using a 3d model isn't an option for me, unfortunately.