How do you get a crowbat in Pokemon Ruby?

You can't get a Crowbat in Pokemon Ruby. Crowbat is a Pokemon that was introduced in Generation IV (Pokemon Diamond, Pearl, and Platinum).

Here's how you can get a Crobat in Pokemon Ruby:

1. You can't. Crobat is not available in Pokemon Ruby.

If you want to play a game with Crobat, you'll need to play a game from Generation IV or later.