I had an issue where I tried to create a custom horse without a BG
It worked, but it was massively out of scale and did not look good at all
Can anyone help me out?
Viewing post in DIY Horse Race Thing comments
From what I've found, I think the problem is the scale of the image. This image is a 2160 x 360 size image; all (or at least some) of the other custom "horses" are 900 x 150.
Basically, you need cleaner images. I suggest taking from either of these sprite sheets, as they seem to have the sprites you're trying to use:
The Spriter's Resource - PMD: EoT/D
The Spriter's Resource - PMD: RRT