Mario Golf - Advance Tour had some characters and course holes locked behind a GameCube-Link feature. This save is right at the beginning of the game with Ella (female character).
No progress at all was made, but all the content otherwise unavailable through normal gameplay is unlocked. A very small amount of experience was transferred to the save to unlock Luigi, as this was the requirement to unlock him.
Mario Characters (Luigi, Bowser, Waluigi, Wario)
Several holes of the Star Marion Course
Several holes of the Star Dune Course
Additional information for nerds:
All the content is already on the cartridge and was unlocked via emulator (Dolphin link emulation)