The GBStudio palette is a strict 4 colors , and Aseprite didn't have it predefined already (which as per the GBStudio docs ) and so I made an easy to use extension here on ITCH.IO! Also, here it is on my website too!
It's the first link right there on my website, and its just a zip file with the two files Aseprite needs to recognize a palette as an extension so it shows up in the palette menu nice a pretty like.
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All you have to do is unzip it (keep the files in the internal folder) in the extensions folder within your Aseprite/data/ install location. Usually, this will be Program Files on windows, or if you aren't sure and own a copy on Steam, just right click the Aseprite launcher, and choose browse local files, This will open up the necessary folder where you can put the palette in and have yourself the necessary colors to make an awesome game!
Enjoy!
iivii
theLibrarian