it's like the player he is sliding on a snow floor instead of running ! Be inspired by Ratchet and Clank, where the hero have a very expressive animation when running , it's somewhat cartoon exagerated animation, but it works very well and bring lot of life in it ! Ratchet And CLank
For the second character that have to crouch, because of 2D view, we don't see why we should croush caus there is no indication : it's hard to see where is the space to crouch ! Perhaps you could make a sensitive button ?
A little idea : Objects between camera and player should be transparent i think , caus when we don't see the character that's really annoying, we don't see if he is standing, crouching or anything else !