You should check the threads in the sector that holds the LE26FV10N1TS chip, that is the flash memory. Put very roughly (but it is not exactly as I say), the threads in the back are inbound communications and the threads in the front are the lines from the cartridge to the GBA system (Do you notice how the threads in the front go from the cartridge to GBA connection pins?). After you check the "inbound" links, check the "outbound" links.
AFAIK, Pokémon games employ these chips to save data:
Macronix: MX29L010TC-15A1, 1m (128kb) flash memory chip.
Sanyo: LE26FV10N1TS, 1m (128kb) flash memory chip.
I don’t know if you can swap one chip-model with the other (it shouldn’t be an issue unless they work differently); however, it is possible to remove an original chip from one cartridge and put it into another.
If it helps, here's a website about "home-brew" projects with Gameboy electronics (including GBA). This link features an -original- schematic of a GBA cartridge; it doesn't have the same layout as Pokémon Emerald, but it could help you to map the relevant connections of your flash chip.
This person took an original Macronix chip from a Pokémon game to make "his own" cartridge.