You cannot directly set Sims on fire in The Sims 2 for GameCube. The game lacks the fire simulation mechanics found in other versions.
However, you can indirectly cause Sims to overheat and faint by:
These actions raise the Sim’s temperature, potentially causing them to pass out from overheating, but they will not actually catch fire. Note that the GameCube version has a more limited feature set compared to the PC version.