So, about exporting and loading palettes, what formats can I use? Tile Layer Pro seems to want a .tpl, but VBA doesn't export in that format
Tile Layer Pro uses it's own format, don't know about programs that export to it. The import feature is, after double checking, for NES and SNES only, and only NESTICLES and ZSNES savestates work.
I'm mainly using Tile Layer Pro for Genesis editing, but this principle should work for every system. Here's how it should work for GBA.
Get a palette viewer or or an emulator with debugger that shows palettes
For GBA there's for example APE:http://www.romhacking.net/utilities/541/
or Visual Boy Advance (this is a tutorial but nicely shows the palette window):http://forums.therockmanexezone.com/topic/747876/1/
Open a palette viewer in that emulator (or another one, we just want RGB values, meaning Red Green and Blue channel values) then input the RGB data into Tile Layer Pro's small "Palette Editor" window, the one showing 16 colors. starting from the top left (1st color there is usually transparent ingame), filling the top row, then the bottom row. Save as .tlp palette when finished. I'm always doing this first with the main character palette, then for stage palettes. If the ROM has uncompressed graphics, you should be able to recognize characters and background tiles now.
Does no one use Tile Molester anymore? I thought it was supposed to do everything Tile Layer Pro did, and more.
I'm only sticking with Tile Layer Pro because I'm used to it and because it has a tile arranger window, which is the fastest way I know to determine how bigger sprites and tiles are assembled from their 8x8 pieces. For the actual editing I've more or less switched to GIMP anyway.