1. Route 11: This is the most common location. Jigglypuff appears at a low encounter rate after you have defeated Brock in Pewter City. It's a good idea to use the "Sweet Scent" TM to increase your chance of finding one.
2. Safari Zone: You can also find Jigglypuff in the Safari Zone, but this is more difficult as it's a rare encounter and limited by your Safari Zone balls.
Here are some tips for catching Jigglypuff:
* Prepare for a fight: Jigglypuff is a Fairy-type Pokemon and is weak to Poison and Steel-type attacks.
* Use a False Swipe: This move will reduce Jigglypuff's HP to 1 without knocking it out, making it easier to capture.
* Throw Ultra Balls: Ultra Balls have a higher capture rate than Poke Balls.
* Consider using a Dusk Ball: Dusk Balls are more effective at night.
Remember, catching Pokemon is based on chance, so don't be discouraged if you don't find Jigglypuff immediately. Keep trying, and you'll eventually catch one!