Bad news, nothing is present in your attached file that can be salvaged.
Save data structure (Generation III) - Bulbapedia, the community-driven Pokémon encyclopedia
Your save file only has blocks 3, C, & D present; everything else is FF FF FF... meaning uninitialized. In blocks C & D, they are all zero except for the box names being present (BOX 1, BOX 2). Block 3 is basically all zero besides a couple of bytes that aren't Pokémon. Nothing to recover, since everything is matching a "new game" state.
Your save data, when viewed in a hex editor, as reference: