How many gym badges do you have to get before getting lugia?

You don't get Lugia by collecting gym badges. Lugia is a legendary Pokémon that can be obtained in various ways, depending on the Pokémon game you're playing:

* In Pokémon Gold and Silver: Lugia is found in the Whirl Islands after defeating the Elite Four and becoming the Champion.

* In Pokémon Crystal: Lugia is found in the Whirl Islands after completing the game.

* In later Pokémon games: Lugia can be obtained through various events, breeding, or trading.

It's important to note that you don't need to collect all the gym badges to obtain Lugia. However, completing the game and defeating the Elite Four is typically a prerequisite for accessing the area where Lugia is found.