Third Generation Contests

Eevee!
The Popular Contest Pokemon Choice
This section only pertains to Pokemon Ruby/Sapphire/Emerald.
Pokemon Contests only exist in Pokemon Ruby/Sapphire/Emerald. There are several types of contests, namely the Cool, Beauty, Smart, Tough and Cute contests. There are 4 ranks, therefore, there are 4 contest halls(except for Pokemon Emerald. There is only one there.). The first contest hall is in Slateport City, where you can get a Pokeblock case(In emerald, the Pokeblock case can be found in Lilycove City). The second is in Verdanturf City, where you start out. The third is in Fallarbor Town, where you go second. The last is in Lilycove City, home of the Master Rank contests. In Pokemon Emerald, all of the contests are held in Lilycove City.

Vaporeon!
The Beauty Contest Pokemon Choice
Basics
There are five types of contests--the cute contest, the smart contest, the cool contest, the tough contest, and the beauty contest. To enter a contest, you walk straight up until you get to the counter. Talk to the receptionist and the receptionist ask if you want to enter a contest. For the beginning contest, you can enter any of your Pokemon, but for the later contests, your Pokemon must have won a ribbon in that category in the previous level to enter your Pokemon. When the receptionist asks you which contest type you want to enter, the screen will place your options in alphabetical order:
Beauty
Cool
Cute
Smart
Tough

Jolteon
The Beauty Contest Pokemon Choice
Pick one and one of your Pokemon and you will be entered as Contestant #4 (This will not change regardless of your ability or how many times you've won a contest.) The receptionist will come out of the booth and take you to the contest field. There will be three other people there. Their Pokemon as well as yours will be presented. The number of ! that you get from the audience directly corresponds with your Pokemon attractiveness. To raise your Pokemon's attractiveness level, you must feed your Pokemon Pokeblocks. If you don't feed your Pokemon Pokeblocks, you will not get any !'s. The harder the contest, the fewer ! you will get even if your Pokemon is feed the same amount of PokeBlock. To get the maximum !, you must feed your Pokemon until your Pokemon's Beauty/Cool/Cute/Smart/Tough is at maximum(You can access your Pokemon's appeal stats when you feed them a Pokeblock.) Feeding more PokeBlock will still give your Pokemon the maximum !, even if you have already touched the edge of the scale. Also, if you go to Slateport City and go to the Pokemon Club where there is a person sitting on a couch when your Pokemon's stat has already touched the edge of the scale, that person will give you a ribbon that will give you more ! when you go to appeal. After the audience sees your Pokemon, it is appeal time! Appealing asks you to select one of your Pokemon's moves. To get the most out of the performance, select the move with the most hearts and the move that is labeled with Tough if you are in a Tough contest and similarly for others. You show 5 moves of your Pokemon and the judging begins. Whoever gets the most hearts in total(from the appealing and audience) get the win! After the master contest, you can participate in the master contest again, but you will not receive any additional ribbons. Also, contests has nothing to do with level. I once had a level 5 Skarmory that won the up to the Cool Master contest. It was just a normal Skarmory, and I got a picture of it drawn in my Pokemon Emerald. An artist will randomly come and draw your Pokemon if he thinks your Pokemon is extraordinary. If he draws your Pokemon for you, you can post it in the museum in Lilycove City. Your Pokemon's picture will also be drawn if you win a contest, but this picture will not be able to be posted in the museum. The picture of my Skarmory is with green outlines, and it is pretty artistic compared to the usual picture.
Strategies for Winning
Manjyome's won more times than I have so we'll wait for his guide