Can you catch a eevee before the elite four in dioamond?

In Pokémon Diamond, you can catch an Eevee before facing the Elite Four. Eevee can be obtained in the game by visiting the Celadon City Department Store in the Kanto region, which you can access after defeating the Elite Four and obtaining the National Dex. However, if you are playing through the main storyline without transferring from other games, you won't be able to catch an Eevee until after you beat the Elite Four and access the National Dex.