Hey there. This document covers creative liberties, and things you can improve.

Creative Liberties:
Changed Golfer's shimmer form to resemble Zoologist's fox form. Thought it was neat if his shimmer looked like his Sister, while his Sister's Shimmer technically looks like his old form.
Didn't edit Pirate's portrait, thought it was fine already.
Removed the blue lipstick the dye trader wears in his default portrait.

Things you could improve:
Some color choices in general. I slightly edited some of the sprites from the original pack, but i'm not a professional by any means.
Portraits could especially use love.
Zoologist's credits sprite where she's detransformed could use more attention. Granted, it's all the way at the end of the game.

If you want to edit the sprites, I highly recommend Aseprite. You can select a color, go to edit > replace color, and change all of the color in a sprite. I used the old sprites as a base for the new ones, and used the Guide's portrait sprite as a base for the new portraits.