In my Pearl, I don't remember getting an Eevee. The girl who made the PC didn't give me one (as it does only work in Platinum, Cutekirlia), but after obtaining the National Pokédex is when Trophy Garden starts to work the way Kirlia explained it. The man says what Pokémon he saw once a day, so soft reset or change the date on your DS until he says Eevee. Then you can run around, catching Eevees till your heart's content. So all you have to do is finish that Sinnoh dex.
I BELIEVE THAT HETALIA SHOULD BE A RELIGION! WHO'S WITH ME?
*cricket noises* What?
...I understand... *sits in corner, eating pasta*