Question

where to find good berrys for beauty in diamond and pearl?

Answer 1

Wiki berries are good beautiness raisers,
they can be given to you by the berry master

then you just need to plant them to get more, good luck.

Answer 2

Here are the best ones that can be gotten easily without an event.

12: Wiki berry- Dry 15 Location: Berry Master

27: Cornn – Dry 20, Sweet-10 Location: Amity Square

32: Pamtre – Dry 30, Sweet 10 Location: Amity Square

The Amity Square ones can possibly be found by walking with your Pokémon in the square and talking to them every 200 steps.