Is always wins the beauty contest? I've never tried before

Neither have I, but if it has a Beauty rating of 170+, it's worth a shot! And I think most of its moves are Beautiful too. Yeah, give it a shot. (I still have yet to get a Milotic )

- DNA

I've got a and I'm feeding him with a lot of chesto berries. I'm gonna try

RayOgre, sweetie, you do know that its Pokeblocks you need to give your Feebas, not just berries, don't you? And that only a few natures like the Pokeblocks that raise beauty, dont' you?

I hope you meant Pokeblocks and not berries. If not, check out the Feebas guide on the main site. (My mistake if you did mean blocks..)

you should probably use higher level berries than chesto-like Cornn or Pamtre

Pamtre berries are the best. If you feed the Feebas about 12 Pokeblocks that are a really high level (like 50 I think), then it's a shoe-in.
I do have to admit I used AR to get a Feebas , but getting to Milotic will be equally as hard. Or will it? My perk was the Feebas was Rash natured. That means that Beauty Pokeblocks will work swimmingly. (I am still working on it actually.)
Here is the Feebas/Milotic guide:
http://www.psypokes.com/rs/feebas.php
He's the most irritating Pokemon to evolve, and thankfully he's worth it.
- DNA

i think the only thing the natures do is determine how much the pokemon likes the pokeblock. it doesnt mean the effect will be any less. eg if you give blue pokeblocks to two pokemon with different natures, it will still raise the beauty of both by the same amount. please correct me if im wrong. but every feebas ive evolved has had a different nature, and some didnt like the pokeblocks i gave them, but they still evolved fine.

No, I'm pretty sure the nature affects how effective each pokeblock is; you might have been able to overcome that by using really good pokeblocks.
And as for Milotic being a shoe-in in Beauty Contests, it's a virtual lock for all but the Master Rank, but even with a good moveset and maxed beauty, it's still very possible to lose a Master Rank Beauty Contest.

thats right. my milotic won it with max beauty, blue scarf, and the moves hail, blizzard, hydro pump, hyper beam. hyper beam isnt a beauty move, but its handy if you happen to be last in the queue on the last turn. hail and blizzard is a combo, and hydro pump is simply a good beauty move. however, to win the master rank, you need to have a little bit of luck. or maybe its more like this: if you have some bad luck you can lose miserably!! well, good luck!!!!

oh, and thanks for the tip jsxtm. i guess it makes sense, although all the pokeblocks i used were made from pamtre berries which make extremely good pokeblocks.

I'm not sure that the nature affects the pokeblock's effect but it may change the happiness. I've used Milotic in the beauty Master rank and won but it was'nt easy.

My Milotic has only Surf and Dive as Beauty moves. Likewise in battles, prediction is key. Surf if you think the one before you use a oblivious move (Protect, Fly, Dig, Iron Defense etc), and Dive the turn after because with six points, you are likely to be the first two with bigger possiblities of being distracted (by Hyper Beam, Psychic etc). Repeat if you want to or use another move. Dive then Surf works too but remember not to use (just about) any move consecutively.