How the original challenge worked
The original Daily Red patch generates a daily six-Pokémon team and lets you face Red in the FireRed battle engine. The creator archived the project and documents a local setup that requires your own clean FireRed ROM.
Where a daily battle is available
The independent Daily Red Pokemon project on the linked site uses a Generation III Pokémon Showdown simulator, gives one local daily attempt and also offers practice. Keep its rules and progress separate from the original FireRed version.