The overlay is just... it doesn't feel right. Can I get some critiques/suggestions on how to make it not so... Idk? Obviously if I do it in black recolor it looks fine but that's not fixing the underlining issues...

And the CI is CRAZY pixelated. How do I fix this? I started with 300x300 in SAI and downsized to 64 with PS

I use SAI for drawing, PS for resizing and adjusting colors

I don't have a ton of time atm to help, but really quick I can give you some item image pointers.

1. Make sure you don't have a transparent background, you need a solid white bg on item images.
2. Make sure to merge your layers before you resize.
3. Since you're working with a huge canvas (I usually recommend sticking to ONLY numbers divisible by the final product) make sure to resize it to 128x128 and THEN 64x64 to help reduce it murdering quality.

@ mesmer thank you for the quick pointers, I will definitely take heed as I did none of the above

Oh that definitely helped a ton, thank you so much @ mesmer

Should I just submit and get official feedback when it gets denied?

You definitely can go ahead and submit to get some info from the queue so other artists can better help you with specifics if you get a denial for it. (Sometimes it's hard to provide help if we don't know how staff feels specifically about where you stand with approvals!)

I do recommend in the future as a general thing though, not to work on too big of a canvas though, at least not until you get used to what the site wants from you. The reason for this is because it's easy to make tons of details on the big size, which are all eaten on the resize. For example, you have all those cute little foot beans and they're barely visible on the actual version you need to submit! I personally work on a 128x128 canvas (also in Sai ;) ) and use a 2px brush for lines. ((If you have trouble with getting smooth lines at all, I HIGHLY recommend using / learning the 'linework layer' function, as it's a MUCH more user friendly tool than the vector system in photoshop lol.))