Originally Posted by Akira
Neither the ROM on its own or under a menu is being recognized as a valid GBA ROM so I suspect it might be a header issue.
You are correct. I just fixed the header with GBA header-tool (by deixu) and it works on the DS. I still need to try on gpSP to see if it fixes the slowness.
Here is the fixed ROM
if someone is interested (with Circle of the Moon header
I have found a small issue. Some power ups from power up blocks "jump" into non accessible areas. For instance, I had some power ups appear in the rock on the left when shooting the power up block located on the left of the first area you have to fall into in level 1 (a bit before your first encounter with a dragon head).