Here's why:
* Legendary Bird Trio: Articuno, Zapdos, and Moltres are the legendary bird trio. In Pokemon Yellow, you can only catch one of them: Zapdos.
* Game Limitations: The original Game Boy games were designed to limit the number of legendary Pokemon you could obtain. This was partly due to the limitations of the cartridges.
To catch Zapdos in Pokemon Yellow, you'll need to follow these steps:
1. Get the Silph Scope: This item is required to see Zapdos and is found in the Silph Co. building in Saffron City.
2. Head to the Power Plant: Zapdos is located in the Power Plant on Route 12.
3. Battle Zapdos: Prepare for a tough fight. Zapdos is a powerful Electric-type Pokemon.
While you can't catch Articuno in Pokemon Yellow, you can find it in other Pokemon games like Pokemon Red, Blue, and FireRed.