I tried looking at the ROM in UNLZGBA, without much luck. It looks like it's not finding the palettes, which is why everything is appearing black, but you can just press the "use black/white" button to see what the graphics appear as. And with that enabled everything I saw looked like garbage, not anything you're looking for.
Just took a quick look in a debugger, and my suspicion is confirmed, almost everything is LZ compressed. I just confirmed this with Soma's portrait, which is located at 5C41E0. I used GBADecmp
to dump the data, and viewed it in Tile Molester, and it's definitely his portrait.
So I'm not sure about using VBA to log the addresses, or why UNLZGBA is failing, but if you have a debugger (I prefer No$GBA, but the debug version isn't free... you may be able to find it by searching though), you can set a breakpoint on 803B9C0, and look at the address in r1. This is called almost everytime data is decompressed, but if that doesn't work, set a bp on 80D813C, which is the actual SWI instruction (for some reason I had problems with No$GBA crashing if I bp'd this address though), it seems to be used for every decompression in the game.
Anyways, I may be able to help you figure out a few things (like how to find enemy tilesets) - I've been interested in hacking AoS in the past, but don't have a ton of time to commit to it, so if you could pick one thing I can help you figure it out.
edit: Just did a bit more debugging, looking into finding enemy tilesets. Unfortunately, it looks the game hardcodes
the addresses of each enemy tileset. This means there is no easy way to just extract all the enemy graphics at once.
Just for fun though, here's a couple I found: (all are lz77 compressed)
81CBF8C - zombie
81F422C - bat