Do you have to beat the battle frontier on Pokemon emerald?

You don't have to beat the Battle Frontier in Pokemon Emerald to complete the game.

The Battle Frontier is a post-game area designed for experienced players to test their skills and earn rewards. It's not a requirement to complete the main story and become the Pokemon Champion.

However, if you're looking for a real challenge and want to collect rare items and badges, the Battle Frontier is a great place to spend your time!