1. Complete the main story: You need to have defeated the Elite Four and become the Pokemon League Champion.
2. Visit the Burned Tower: After becoming champion, the Burned Tower in Ecruteak City will be open.
3. Talk to the old man: Inside the tower, speak to the old man who will tell you a story about three legendary beasts.
4. Find the legendary beasts: After speaking to the old man, you can encounter Entei, Raikou, and Suicune randomly in the Johto region.
Here are some tips for finding Entei:
* Focus on areas with grass and open fields: Entei is most likely to appear in grassy areas like Route 38, Route 39, and the National Park.
* Try using the PokeRadar: The PokeRadar is a useful tool for finding Pokemon in specific areas. Use it to scan the grass for Entei.
* Use a lure: The "Shiny Charm" is a great item to use. It increases the chance of encountering shiny Pokemon, which means you'll also increase your chances of finding Entei.
* Be patient: Finding legendary Pokemon can take a lot of time and effort. Don't give up!
Important Note:
* You only need to visit the Burned Tower once to trigger the appearance of the legendary beasts.
* They appear in a specific order - first Suicune, then Raikou, and then Entei. However, they don't necessarily appear in these locations in this order.
Good luck finding Entei!