Question: is eevee in omega ruby?
Answer: You can get it after you have successfully defeated or captured Groudon or Kyogre, and you need to go to Littleroot Town and talk to Professor Birch. He will upgrade your Pokedex. Go to Route 116 near Rustboro City. Here you will find Eevee and other Pokémon such as Nincada and the common Zigzagoon.