Sorry for 2x posting, but I have 2 screens showing power-up revamps:
The star was simple, as well as the fire flower. I made the fire flower use palette C via Tweaker.
The mushroom respects the theme.
For the feather, I used the one from Mario wiki as reference and corrected it to use the YI style.
For the 1st level to be done, I need to draw the Whimp. Unfortunately, it ends up being hard to do it in YI style and there's like little reference to it. Any help will do.
Edit: I'm starting to draw the whimp YI style. Progress is really good. When done, I'll release it on the site, since there are no GFX for such sprite, except 1.
Edit2: The YI Whimp is done. Instead of seeing it, you can check it out here