How do you get pinsir in Pokemon LeafGreen?

You can't get Pinsir in Pokémon LeafGreen. Pinsir is exclusive to Pokémon Red and Blue.

Here's why:

* Generation I Game Exclusives: Many Pokémon were exclusive to specific games in the first generation (Red, Blue, and Yellow).

* No Trading: LeafGreen lacks the ability to trade Pokémon with other games, making it impossible to get Pinsir from another source.

If you want a Pinsir, you'll need to play Pokémon Red or Blue or use a trading system outside of the game.