Here's what happens:
* No further challengers: You'll be told there are no more trainers to fight.
* No further rewards: You won't receive any further rewards like items or money for defeating trainers.
* Continued access: You can still access the Battle Tower and battle against the trainers you've already defeated.
* bragging rights: You can boast about your accomplishment and challenge other players to see who is the true Battle Tower champion.
Remember that the Battle Tower in FireRed has a fixed roster of trainers and their Pokémon levels, meaning you'll eventually reach a point where you've defeated everyone. However, the challenge lies in perfecting your strategies and building a strong team to conquer them all!