A lot of people, including myself, have always found it hard to find Entei, Raikou, and Suicune for the first time. After that it's easy since you can track them with your Pokédex but relying on luck for that first encounter takes a lot of luck and patience so here's a method I figured out that makes it a bit easier. What you need: -A Pokémon under level 40 but higher than Jhotos wild Pokémon. -Repel, a lot of it. Super is best for getting the most mileage for your Pokedollars. -Patience. -Luck. 1. Fly to New Bark Town. 2. Put aforementioned Pokémon at the top of your party. 3. Go to the first route. 4. Use repel and wander in the grass until you encounter one or use 1-2 Super Repels. 5. Go to Cherrygrove and the route north and repeat. 6. Keep going until you reach Olivine by going through Violet City, and Ecruteak City. Don't use fly. 7. If you didn't find them all, fly back to new Bark Town and repeat. Using this I found all 3 in under an hour.
Nice, It sounds pretty useful, since the beasts are level 40 you can use a 38-39ish mon infront of the party and have your trapper/sleeper at the back. thanks!
I do that, but to simplify the walking bit I just go to Eucreteak City and walk in-and-out of the southern exit until they show up on that route. Takes a bit of time, but they always show up.
Yup, this is a pretty solid method! I pretty much did the same but instead would just go back and forth between the same routes.