go from violet city through route 36 then up toroute 37 and that's how.
you go to ecruteak city
You'll need the Rainbow Wing from the Radio Director and then go to the Tin Tower in Ecruteak City.
go directly right out of ecruteak city :)
Go to Ecruteak City and go to the house on the left side of the Pokemon Center.
When you first go to the Ecruteak Poke-Center you will find him. Then you can find him in a small house in Goldenrod City, he will give you an Evee.
When you enter ecruteak city go left until you find an entrance for mt mortar [But you need one of your Pokemon to know flash if you want to enter mt mortar]
Start from Ecruteak City and go to the right and out of the city to Mt. Mortar!
Simply go east from Ecruteak City
you use a pokemon that knows fly and go to victory road and fly to ecruteak city in johto
To get to Ecruteak City, you need to defeat Whitney (the gym leader of Goldenrod) and then talk to the girl in the house next to the gym. She'll give you a Squirtbottle to rid the Sudowoodo on Route 36 and get to Ecruteak. My game, however, has a glitch that allows you to go to Ecruteak, Olivine, etc. before beating Whitney. To do so, go in front of the Sudowoodo and into your party and select Cut from one of your Pokemon. BAM! The Sudowoodo is killed.
You can't find Eevee in the wild, but you get one from Bill after you find him in Ecruteak City. He will head back to Goldenrod City after you talk to him, and if you go to his house in Goldenrod, he will give you Eevee.
You may know this already, but there is a sleeping Sudowoodo in the middle of the route to Ecruteak City. Therefore, you cannot get there. To get rid of the Sudowoodo, go to Goldenrod City, enter the side street on the right and visit the Flower Shop. Talk to the girl inside and she'll give you a water can. Then go back to the Sudowoodo and press A on it. The water can will be used on it and you will have the opportunity to battle it. After battling it, the route to Ecruteak City will be unblocked and just follow it to get there!