While simultaneously scaling you want to animate the bones Skin Model Character

I use Android Pro and iPhone Pro.
Unity3d Version 3.304.

By extending the bones SkinModel, I think trying to change the mind free to body.
Skin on the Android version because I do not know where that will be animated,
I do not know how to animate the bones stretched.
I think an easy way to animate the bones stretched?

Provided your animations do not set the scale, you can freely scale the bones in your object, and they will animate as expected (i.e. just rotation and position will change).

Note that at least with Blender FBX I/O, even animations which you do not design with scale in them get them when imported to Unity. I use a big ugly script to strip them out.

To see if your animations have the scale set, select the animation in an Animation window and look for coloured buttons (not grey) near the localScale variables.