Which pokemart do you go to so you can battle deoxys in pokemon diamond?

In Pokémon Diamond, you can battle Deoxys by going to the Pokémon Mart in Veilstone City. However, you need to unlock the event by having the Hall of Origin event item, which is not available in the regular gameplay. Deoxys can be encountered in the game through special events or by using certain cheat codes. If you have access to a legitimate event, you would typically use the Hall of Origin to encounter it.