De-Rusting my Spritings- NES SMB Chell

[Vipershark]

I actually really like these!

The only problems I see so far are that sonic's shoes seem way too long and... angular.

I made a quick edit (the left one)

That, and Knuckles' shoes seem hugely disproportionate to the rest of his body.
Sonic's shoes are 7 pixels tall at their highest point while Knuckles' are 9 pixels tall. Since Knuckles appears to be shorter than sonic, this makes his feet appear to be huge and clunky while his legs are stubby.
You should make his shoes the same size or smaller than Sonic's.