Please clarify
Unfortunately no. While it's possible to run a GB Studio game on the GBA, we won't accept it as it would be against the spirit of the jam. There's a fair chance our friends at gbdev.io will be running a jam later in the year, so keep an eye out for that :)
[edit] We now accept GB Studio games if they are compiled for GBA using gbsenpai.
https://github.com/asiekierka/gbsenpai
this awesome human being tells us how to port gb studio games to the gameboy advance