This is a look at which berries i've used to get max Beauty, Cool, Tough, Cute or Smart stats for my pokemon in Diamond or Pearl.
you need close to Max beauty (170 or higher) to get your feebas to evlove into Milotic
using these berries you should have no problem maxing out your Stat

Here are the Steps to getting max stats
use the following berries for poffins
31. Spelon berry (cool)
32. Pamtre (beauty)
33. Watmel (cuteness)
34. Durin (smartness)
35. Belue (toughness)

all these are randomly found in amity square from any of the pokemone able to walk around in amity square.

You want to try to turn these berries into level 25 or higher poffins because you will only be able to feed you pokemon 8 of them and you need the total level of the poffins to equal 200 or more.

you will know thst you have max stats if you are able to get a scarf from the girl in pastoria city