What happens if you beat the elite four ten times in firered?

There's no special reward for beating the Elite Four 10 times in FireRed.

Here's why:

* No in-game feature: FireRed doesn't have a system to track how many times you've beaten the Elite Four.

* Post-game content: The game is designed to be completed after beating the Elite Four and becoming the Champion. There are some post-game activities (like catching legendary Pokémon), but no additional content for repeatedly beating the Elite Four.

In summary: While it's a fun challenge, there's no in-game benefit to beating the Elite Four multiple times in FireRed.