Easier way to win contests!
Now, remember Vielstone Department store Go to the bottom floor (B1) and talk to the person that sells poffins. Pick a pokemon you want to use in contests and check what type of food/poffins it likes (my Charizard likes sweet food). Buy as many of the type of poffins (Ex.Sweet/Sour). Give them to your pokemon and eventually their condition in Cute, Beauty, etc. will will get higher and higher. Remember what stat goes up depends on what kind of poffin you use. When one stat is very high, enter your pokemon in a contest where they have a high stats (Sweet=Cute) and they'll do better in the Visual contests! If you win the Master Contest check your trainer card and you'll get a surprise!
P.S. There is a guy in Pastoria city who checks your pokemons beauty. Bring your contest pokemon to him BEFORE you enter a contest and he'll give you a scarf that enhances your pokemons stats for contests.